Just to start, let me say that it's been very hard to figure out just how SW's snapshot works, and I've had to do a lot of experimenting myself to really figure out the specifics, as there are a lot of conflicting reports online. I've deluded myself into thinking one thing works for a period of time, only to discover later that SW's snapshot was negating my whole strategy, (swapping to a Maximus to gain the +Fire Skill damage is inneffective, as is Flying Dragon's 2x Attack Speed). After a couple weeks of trial and error, I think I've finally gotten it figured out.
The best way to snapshot your SW is to maximize Crit Damage, Dex, Base Weapon Damage, and +SW damage (or the corresponding +elemental skill damage) before you cast sweeping wind, as these stats are all included in the snapshot. Life Steal is also included, so if you need extra survivability, you'll need to have LS on your Skorn (though you probably wont need it). Attack Speed and Crit Chance need not be snapshotted, as your SW damage will increase as you increase those stats even after you cast SW.
That being said, here is how I gear swap:
I am currently switching 5 pieces of gear. My Ammy, Gloves, Helm, one Ring, and my Weapon. My starting Amulet and Ring have +Damage, high +Crit Damage, and Dex. My gloves have High +Crit Damage and Dex. My Weapon is a 1440 DPS skorn with 200% Crit Damage and no IAS. My Helm is a random rare Helm with +12% SW damage and high Dex.
I am currently switching 5 pieces of gear. My Ammy, Gloves, Helm, one Ring, and my Weapon. My starting Amulet and Ring have +Damage, high +Crit Damage, and Dex. My gloves have High +Crit Damage and Dex. My Weapon is a 1440 DPS skorn with 200% Crit Damage and no IAS. My Helm is a random rare Helm with +12% SW damage and high Dex.
After getting DR/Foresight bonus, I cast Blinding Flash/Faith in the Light and then SW/Fire Storm, and switch into High Crit Chance Ammy, Gloves, and Hellfire Ring (you can't swap in your SOJ without losing the +SW damage). I switch my helm to Inna's Radiance with a Radiant Star Ruby, 6.0 Crit Chance, and 2+ Spirit Regen, and, this is key, and I believe a new innovation, a Diabo with +2.45 Spirit Regen. making my post-swap gear grant a massive 6.4 Spirit Regen.
Of course, I also use a Templar for more spirit regen, and he wears a Leroic's Signet and a Hellfire Ring for the bonus XP.
The beauty of all of this Spirit Regen on gear is that I don't need to use MoH/Circular Breathing OR SW/Inner Storm to maintain my Spirit during TR. I use all 3 Passive Spirit Regenerators, and that is good for all the Spirit I need. I even have enough to pop MoC/Overawe before I run through Hulking Phasebeasts and Elites, allowing me to one shot even the largest white monsters and kill Elite packs in about 2-3 seconds, with a Blinding Flash to keep them stunned and inside my Fire Storm. I still need to use a skill slot on Serenity to keep myself from getting frozen after the pack dies or getting ganked by Reflect Damage.
The run I use is modified to allow me to never have to refresh SW. Start at Azmodan, work backwards all the way through the towers and craters, go through Seigebreaker's zone, and continue all the way to the Fields of Slaughter, clearing the zone and making your way to the waypoint. From here, I go to the Keep Depths level 3 and work my way back up to town. From there, I use the door to get to Skycrown Battlements, and work my way to the end of Stonefort where my run ends. This method allows me to NEVER have to take a town portal, which is awesome because, barring a lag spike, I never lose SW and never have to do a second gear swap.
Here are some potential improvements that I haven't tested out yet but spark my interest:
(1) Use a leoric's signet on yourself instead of the SOJ, and make up the lost spirit regen with Circular Breathing. You'll take a DPS drop but the bonus XP could certainly be worth having to double back every once in a while to finish off mobs.
(2) Use Circular Breathing to allow yourself to get IAS on your gloves, ammy, and hellfire ring without making TR cost too much. This might just cancel out the bonus damage from Overawe, but it might be slightly better or worse.
(3) Use a +Spirit Regen Inna's Reach to complete the 4-piece set, and swap out Inna's Favor for a legacy Hellcat Waistguard. This is ridiculously expensive, but I think it would be optimal if you can afford it, as it would certainly let you skip the SOJ and equip a Leoric's signet, or just let you skip Exalted Soul and allow you to equip Fleet Footed, which could help you just as much as the bonus XP if your SW damage is high enough to still one-shot white mobs.
(1) Use a leoric's signet on yourself instead of the SOJ, and make up the lost spirit regen with Circular Breathing. You'll take a DPS drop but the bonus XP could certainly be worth having to double back every once in a while to finish off mobs.
(2) Use Circular Breathing to allow yourself to get IAS on your gloves, ammy, and hellfire ring without making TR cost too much. This might just cancel out the bonus damage from Overawe, but it might be slightly better or worse.
(3) Use a +Spirit Regen Inna's Reach to complete the 4-piece set, and swap out Inna's Favor for a legacy Hellcat Waistguard. This is ridiculously expensive, but I think it would be optimal if you can afford it, as it would certainly let you skip the SOJ and equip a Leoric's signet, or just let you skip Exalted Soul and allow you to equip Fleet Footed, which could help you just as much as the bonus XP if your SW damage is high enough to still one-shot white mobs.
Tempest Rush is one of the most fun skills in the game, and I've blown a lot of gold theorycrafting and trying out fringe builds just so I can run around at super speed. The only caveat I have is that after a few weeks, you'll never want to slog around at 24% move speed with FOT/Thunderclap equipped ever again. Have fun, and happy rushing!
My build, post-gear switch right now. As you probably know, this is unreliable because at any time things might change, and I'm always experimenting: