One area in which I'd suggest treading cautiously is Sean's endorsement of the old, gigantic, 90mm f/2 Summicron, the one with the built-in tripod socket. This is the only non-current lens he tests in the review, presumably because one of his sources made it available.
I had one of these and found it almost useless because when photographing bright objects against dark backgrounds, it produced a very pronounced double image of the highlight. Sean's subjective test scenarios don't include a situation that would provoke this, and maybe your photography doesn't, either, but beware if it does.
I eventually ditched my old-style Summicron in favor of an LTM 105/2.5 Nikkor, which was dramatically better in every way, and later replaced that with a 100/2 Canon, which delivers both quality and speed. But I guess none of those were available to Sean as loaners...