Well, in my experience, vinegar might have the ability to affect LSPs, but not anything major. I suppose this all depends on the LSP....
However, due to my water, I always have to do a vinegar wipedown after _every_ wash

. My ONR QD and "NXT speed detailer" (not really good anyway) just get laughed at by the water spots that form within seconds of a rinse.
I've done a vinegar wipedown twice thus far on my current LSP and my 845IW still beads nicely (in the 845 way of beading, so at least I know its not just the paint that's beading) and looks great after a wash. Of course, if I had the time, I'd put on a coat of Max Wax after each wash. Aquawax would do it too... but I've been on a carnauba craze lately so I just can't bring myself to "waste" time with AW heh.
Regardless, water spots aren't really from the wash solution per se. It's mostly from the rinsing... which comes straight from the hose. Not much you can do there unless you get an inline hose filter like this:
Garden Hose Filters
Or, like joyride said, get a CSRSpotless uint - although those are significantly more expensive. However, you're guaranteed a spotless rinse with the second option.