i've only had one Vaper's Cloud RTA, a 25mm VCMT2, and that was atrocious - basically it was flavourless unless you ran it at ridiculously high power levels - and then it was prone to dry hitting. However, that was a 6 year old design - but it was pretty crap compared to most Chinese RTAs available at the time that were half the price.
I couldn't say about their RDAs, but I get the impression most are designed for high powered cloud-chucking, rather than flavour, but I could be wrong. Personally I wouldn't.... but all my favourite RDAs are 24mm and I think the smallest they do is a 25. I believe they actually market a 30mm RDA as a mini because they have a 40mm version in the range. A 30mm RTA may be large, but the coils are enclosed in a, much smaller inner housing so the deck generally isn't much bigger than a 24/25mm RDA - A 30mm RDA has a lot of space inside and, unless you run it at pretty high power levels the flavour can suffer. Not for me, but I don't vape at high power levels often enough to consider buying one.