I have one. It's just okay. It's great for finishing things melting cheese on dishes, etc., but it's a little under-powered for searing a steak nicely, especially if there's any moisture present. It's fine for one steak. For two or three, the first would get cold before the others were ready.
If, for example, you were intending to prepare a meal for yourself and your romantic partner, I would recommend getting two. I doubt there are many things more attractive than being fed tasty food by a person dual-wielding a couple of torches.
Trying to use two at once sounds dangerous, and you'd lose the ability to move the meat around so that searing the edges of the steak would be very difficult. An equally sexy option is a deep fryer.
I've found that the searzall has a relatively steep learning curve. The learning curve is more like a knife than a pan. The kind of person who is buying the searzall is probably not used to being unskilled with a kitchen tool; I certainly wasn't.
I've successfully seared four porkchops with it, with none of them getting cold. The trick is getting each chop up to the searing point, where you can see bubbling on the surface, and then keeping it there. It's a little like spinning plates. You have to get them all going, but once they're there you only need to give each a little push once in a while. That also gives me a more satisfying crust than if I blitz through in a single pass.
Searing both before and after the immersion circulator is a strong option. I believe Dave Arnold recommends it (or deep frying) for folks interested in maximum crust formation.
It's really a transformative tool because it allows such high heat with such fine precision. It's my preferred tool for cooking the top of an egg that I still want a runny yolk. Also useful in any kind of home pizza-making. I've occasionally brought it to the office, though only when there's an outdoor space I can use.
Oh, the egg thing! I've done that. It's great for that. Definitely brought mine to work to crisp up an entire porchetta. I want to try it on steak that's been reverse-seared, I wager that starting with a dry surface will work much better.
Yeah, that's my impression too, you need to pat them very very dry, which might take time if you sear them directly from e.g. a sous vide bag. I still use it to sear single steaks, because the fire alarm is a bit overzealous and the searzall creates less smoke than a Cast Iron skillet.
If, for example, you were intending to prepare a meal for yourself and your romantic partner, I would recommend getting two. I doubt there are many things more attractive than being fed tasty food by a person dual-wielding a couple of torches.