WHY?
Switching to DOT 5 is not necessarily an improvement.
Yes, DOT 5 will not typically harm paint, plastics, etc. True also, that it won't absorb moisture. Yes, it will last longer in your brake system. Yes, it has a good boiling/freezing differential. There's a couple of other benefits, I'm sure.
But wait a minute! DOT 5 is silicone based, and therein lies a little flaw. Silicone defies the laws of physics (well, at least it bends them a little). Liquids do not compress, as you probably already know. Silicone, however can emulate fluid compression, in that it a given volume of silicone can be made to occupy a smaller space.
What does that have to do with your clutch, or brakes? Well, it's simple. Under hard braking, especially when your fluid has become hot, something awful can happen. Let's say that you panic brake, your brake pads, rotors, and fluid is hot. You squeeze the lever to the grip and...that's right, you don't stop. Why? The silicone based DOT 5 has compressed, and you could not supply enough fluid past the piston to push the caliper pucks against the pads to squeeze the rotors with enough force to effect a stop. To get out of that situation, you would have needed a force-multiplier, or a master cylinder with a re-sized bore.
DOT 4 is uses glycol. Glycol can ruin plastic, paint, certain types of rubber. DOT 4 also should be replaced in your clutch, or brake system every two years, as it will absorb water, and that ruins hydraulic systems. But, DOT 4 behaves according to the laws of physics. That's a real plus for us bike enthusiasts. What DOT 4 will do, is give you a very good feel for your brakes. Since it does not compress, it is predictable. Your brake feel will be positive at the lever. As we have only two wheels on the road, positive feedback from our brakes (or hydraulic clutches) is imperative.
If you want to REALLY make an improvement, I would suggest braided lines, and a combination of pads and rotors that "hook" better than stock. If you want to really go nuts, radial master cylinders, and some high-end calipers, such as Brembo. What fluid would I recommend...personally, I'd stick with the DOT 4.
Have a look at what lots of other manufacturers, both car and motorcycle, are using. Even Harley-Davidson finally stepped up and uses DOT 4 (Brembo calipers too). You'll find the majority of brake systems out there use DOT 4.
If you do decide to go forward and switch to DOT 5, I would suggest changing ALL the rubber (Buna-N, Nitrile, etc.) in your brake/clutch system, as well. The longer your rubber parts have been exposed to DOT 4, the less likely they will be to happily accept DOT 5. Your o-rings, seals, etc. can become swollen by the addition of DOT 5, or even become soft, and disintegrate. I would STRONGLY suggest that you do a full rubber swap if you do the switch, as a brake failure, or leaks are a real bummer.