I don't know where you're getting a price like that for Kneadatite - a 36" ribbon lists at about £6.35.
I've not used Aves, although it sounds similar to milliput etc.
I have used Milliput & Kneadatite for 28mm - they handle completely differently so depending on what you want it will take a lot of time to practice with green to do the same job.
Kneadatite is a bit like chewing gum, personally I had difficulty with the rubbery 'memory' of it, and getting the right amount of lubricant to stop it sticking to every tool i have (too much and it ends up not sticking to itself) as it's best layered up. What it does do well is small fine detail as the consistency doesn't separate or crumble as other epoxies can do if you're not careful. I guess that's why a lot of miniature sculptors use it, plus it will withstand vulcanising of rubber moulds.
Unfortunately, the kneadatite I have I left at home in the freezer, otherwise I'd send some to try out for free. ( I put a box together of modelling supplies to play with while I'm offshore and forgot to go in the freezer...)