If you liked your mates TRX4 then i would suggest going with that as it already comes with some of features your looking for and others may be able to be added later
To be fair im not sure what else is out there in kit form
Have you had a look at the news pages as theres been a few new crawlers announced and spec wise they seem pretty decent
Your mates TRX4 has it been modded at all ?
Ive modded mine a bit with low down brass parts like brass portal covers etc