I'm buying a second guitar soon, the first of any reasonable quality, and I've been considering getting an Ibanez S320.

I originally wasn't going to consider it, as I swap between E standard and dropped D quite a lot, so didn't want to mess around a tremolo. But I've read on some topics/forums that the Ibanez ZR tremolo can be swapped pretty quickly and painlessly between tunings by fine tuning the low E string (or something like that ).

So is this BS or not? If it's still something to do that takes longer than a couple of minutes, I'll probably consider a RG321 or something from the SZ/SZR series.
the ZR is very easy to tune imo, just unlock the string at the headstock, use the tuner to get close to what you want and lock it, then you have a thing you can fine tune it down on the bridge
Inspired by Ibanez RGA321F Prestige, Gibson Les Paul Standard
Powered by CAA OD100 standard+ , Mesa 2x12
Affected by Maxon OD808, Mad Professor Deep blue delay

AFAIK a lot of guitars can reach Drop D just using the fine tuners at the bridge. It's worth a try
Schecter C-1 Hellraiser FR <3
Every floating tremelo requires the springs to be adjusted when you switch tunings, even if it's just to something like going to drop D with the fine tuner. The other strings will go out of tune if you don't. It may be subtle and you may not notice, but you're still out of tune.