Hi mate welcome to S.O.C
I'll start with I wouldn't worry about owners more so with these cars, I have seen so many people say about this. Yes it could be because it's a bad car and is getting shipped off every few months because people don't have the funds to look after it. But I have seen a few that have had a lot of owners and are still great cars. People will buy these then realise it's not suitable for their needs we have had someone this week post and say Hi then matt see the same car on ebay :( Like my car it was sold and bought by the same owners 5 times back and forth I still have no idea why. And it's an early 2001 bugeye. Not to saying Snoop-y is wrong, but more for food for thought or looking into the paper work. But I agree MOT paperwork doesn't always mean anything but no advisories is good unless done from the same Garage might have been a backstreet garage.
The prodrive pack is nice to have and would say it's been looked after but I would always want some sort of paper work with it. For me out of the 2 you have listed I'd maybe go for the 1st one and use the extra money to spend on mods it doesn't cost loads to soon tune them to 300BHP and thats a WRX you can go to 350. which is past a STI standard anyway :)
All I can say anything second hand is a gamble it really is. You could go VW, Ford, Vauxhall, and still have problems. Like the lass next door to me got a Vectra well damaged not much in the way of paper work. Had no oil in the gearbox at all luckily spotted that and it's still running for now that was last week, but starts ok and no problems with gear change at the minute so think it was saved. Just annoyed I now have to buy some more oil for when I change my calipers :D
Anyway I'd look at both take for test drives we have a guide HERE
Has some of the members add to this so worth looking into and having a read down the list. But Clutch gearbox Big End failure and Headgasket is the big worry at the end of the day. The brake calipers do suffer from stuck pistons also but thats not a problem we have a chap on here that refurbishes them for a living on here :) So if you take them both for a test drive, report back anything worrying you. That will be better off that way as a report back on both car, all being well give us more insight :)
I also found looking further for these cars was a great help, to find one you're completely happy with I traveled for both mine :)