I've loan swapped (and simply loaned or been loaned) dozens of machines in the past. From less than year NIBs to much older machines. Some with people I hadn't even met before!
(My Imdn for his Kiss)
The usual agreement is that basic maintenance, such as rubbers and bulbs are replaced by the person in possession of the machine at the time, larger items such as DMDs, node boards etc are replaced by the owner of the machine (assuming failure not to abuse)
It's a great way of getting to experience different games, which you may not be able to afford, rarely come up for sale, or you don't want to let go long term. I'd have been horrified to have actually bought Hook, but glad that I got the chance to play it and put some time on it and learn the rules. Likewise I would never have been able to afford BM66, AcDc or TWD (amongst so many other titles in my signature) but got to play them at home.
It's also a great way to see other peoples full collections in situ and put up some graffiti.
Never have I asked or even looked how many games have been played.
It's much easier when you actually meet people in real life at shows, comps or league meets and get talking to them.
EVERY single machine I have borrowed has gone back to their owner in at least as good condition - cleaned ,re-rubbered, new balls etc. I've also never had a machine come back to me in a worse condition than when it left me. People tend to take better care of someone else's machine than their own.
A loan swap is the way forward, and always has been.