In the AT4 era, I went for AT4 MAX and then added a number of packs, including the Fender Collections and Leslie. In the AT5 era, I have acquired AT5 SE and, as promised, I have a fully-functional AT5 rig with all of my AT4 gear available in it. So far so good. Then GAS strikes. I have several times got as far as putting AT5 MAX in my shopping basket, but then I look at the new gear that I will get with it and the gear that I already have by virtue of my AT4 era investments and decide not to proceed.
What would make me upgrade in an instant would be a pricing structure that reasonably reflects my earlier investment in the AT4 era. That is, something which recognises that I have already acquired a substantial part of the gear between AT5 SE and AT5 MAX and hence discounts the AT5 MAX price accordingly.
I can't be the only longer-term user who gets caught in this trap, so pretty please IK Multimedia!