I didn't want this thread to turn in to a debate about whether passive setups are more reliable than active, but as a mechanic I feel I have to say that in my experience electrical connections that can't be soldered (or permanently tightly crimped) are far more likely to give trouble...
e.g. - even though my bass from the rubbish spent time outside in the rain before I rescued it, I soldered one wire back on that had pulled off (probably when the PO was trying to break it in half!), sprayed RP7 in the pots and haven't had to touch the electronics since - and that was well over ten years ago.
I have some great suggestions in this thread so I know what to keep an eye out for. (In a lot of cases it is far from obvious whether or not a particular model has a battery hidden in it somewhere!)