A few months ago I converted my front and rear wheels to the Tubliss system to eliminate the need for inner tubes. Although I haven't had much time to ride (and the weather hasn't exactly cooperated either), so far the system seems to be working well.
One issue has been balancing the wheels. There was a lot of vibration with the bare Tubliss setup, particularly in the front. Stick-on wheels weights did little to help, and there's not much of a flat space on the WR250R rims for them anyway. So I ordered an additional two 30g spoke weights for the front. Combined with most of a bottle of Slime, this seems to dynamically balance the front OK, although testing with the wheel off the bike still shows the Tubliss valves area to be heavy. It's frustrating, because I don't want to clamp a whole bunch of weights to my wheels. Haven't attempted to balance the rear. I don't notice any rear vibration at the sedate 80-90 km/hr max that I typically ride.
Tire and inner liner pressure has held up remarkably well from week to week, losing nothing noticeable from the tire and only a pound or two from the 100psi liner. That's pretty impressive considering my road bicycle tires (which normally run around 100-120 psi) lose far more than that. There's a bit of Slime leaking out from around the valves, but only a drop or two. It's probably just some of the juice I squirted in there while mounting the tires.
Still keeping my rides close to home for now until I can be sure the Tubliss was mounted correctly and is reliable.
Update July 21, 2014: Tubliss removed.