I have both I prefer the A4000 why? Less headache on the A3000 my zip ram started to act up as some said pain to try and find which is the bad one I opted to use a sim to zip adapter still had to make sure everything was aligned.
It took me much longer to clean and make sure everything was working on the A3000 then A4000 (speaking from a normal person stand point which you are as well ie not an expert electronics tech) taking it apart was also a pain, but come down to what you want to use it for, quite frankly now that my A2000 has an indivision i use that more then the A3000.
The computers i use the most are in order:
A1200
A4000
A2000
A500
C64
an A3000
Unless you have a video card in your A3000 you not going to like the output (trust me).
As for caps they "may" fail but i have not had one yet not to say i will not replace them at a later date and apart from the guy in France there is an Amiga repair guy in New Zealand and Australia also i think Amigakit do repairs (not sure)
For less headache i would go the A4000 route with indivision as even with the A3000 you have to find a monitor that works (crt are ok but tft ...... )
