PowerVision is going to give you significant performance over the HD tuner. Night and day, no debate. Now, when it comes to warranty, you need to remember a few things. First, your dealer needs to keeps it's service dept busy, so they are going to work to submit claims. Where you will have the issue is if you have a major problem, and HD has to come inspect the bike, OR, you are on the road and visit a dealer you don't have a relationship with. You can flash your PV back to the stock map.
I'm due for my 1K service, going in next week. Once I get it back, I'll load my PV, and install a new headpipe. If I end up having a major issue, I'll replace the headpipe, reload my stock map, and bring the bike in. Worth the hassle, the 117 in my CVO needs to wake the &^%$ up.