I used contact micros for a long time and recently converted to spaced micros. I wrap the same coil, about 1/16" of 28ga Kanthal at 1 ohm wicked with rayon for use on a mech, but now I stretch it out on the nail and squeeze it back together, which has it spring back out creating small and fairly uniform gaps.
The reason I tried gaps is I vape gunky NETs and heard of reports of it gunking slower than a contact coil. Turned out for me that it's absolutely the case, when using rayon anyways. A dirty NET that before would gunk a coil to a point of being unusable after 2ml on a contact coil has been able to go 4+ml on my new spaced micros. Quite a drastic difference that others had reported but I didn't believe until trying it myself.
I have no idea why this is the case, but it was easily provable for myself. If someone knows the science behind the mechanics it would be interesting, because it's a mystery to me. I previously noticed that rayon gunks slower on a contact micro than the KGD cotton I used to use (no idea why that is either) but the result was more drastic moving to spaced coils.
As far as quality of vape and heat up time, surprisingly I'm not really noticing an obvious difference. The vape is basically the same, but now I dry burn less. If someone vapes clean juices I don't see any reason to switch from one style to another, but if someone uses contact coils and dry burns a lot they may want to try spaced. Just small gaps works for me.