I'm thinking of shortening my boil times also - not quite down to 5 minutes, but maybe 45 on my next batch.
I often do 45-minute boils, even with pilsner malt. Never had a problem with it, just have to increase the bittering hops a little when moving them up from 60 minutes.
I've done a sour beer with no hops and no boil, and that turned out good. (a little weird, but good) This will be the first time I try a 5 minute boil and bitter it with hop tea. (it's supposed to be no-boil, but I want to sterilize the wort to make it less likely that I contaminate my expensive new yeast strain before I get a chance to harvest some. Next month I might try a real no-boil version like I've read about from Lithuania.