I've also been using DOT 5 for several years and am glad I made the switch. No matter how careful I am, I still end up with Brake fluid on the components. The Z1R's have a unique remote M/C that are notoriously difficult to bleed. The front of my bike wouldn't have any paint if I had used DOT 3.
DOT 5 does not absorb water, and as others have mentioned, this could lead to corrosion in the lowest points. However, I've replaced numerous caliper pistons and pitted M/C's in systems with DOT 3 fluid. DOT 3 fluid may absorb some moisture, but it is not immune to corrosion without regular maintenance and flushing either.
DOT 5 does aerate, trapping tiny air bubbles when shaken. HD uses DOT5 as OEM in some models. They recommend leaving the bottle sit undisturbed overnight before use. Don't bring the bottle home and pour it in. I think this aeration also adds more time to bleeding a DOT 5 system. You could have good solid lever pressure, and come back the next day to a spongy lever, The tiny trapped bubbles form into bigger bubbles and need to be bled again. Plan on repeat bleeding over a few days with DOT 5.
IMO, DOT 5 gives a slightly less firm lever feel and is more prone to leaks than DOT 3. Your brake system needs to be in good condition to use DOT 5. If you've got a marginal seal, you'll find it with DOT 5. Since you basically need to rebuild your system to switch, and are probably going to replace all seals, this shouldn't be an issue.
