500 4 stroke trikes were fun, far less gear changing than the CR250 engined ATC250R's. The scary ones were the 500-ish 2 strokes, The RM465 version was a weapon. The problem was keeping the front tyre on the ground, a bike you can do it reasonably easily but regardless of the surface a solid axle trike has probably 5 x or more traction especially with flat base rear tyres. I always wanted to build one out of an IT490 but could never buy one with a good enough engine in it; the bikes were always good but the engines flogged out. I was looking at my DR650SE the other day and it'd be easy to convert one of these that was a stat writeoff (bent front forks and mangled front tyre will do it) into a trike.

If you get a chance have a ride on one, but if you are an experienced two-wheel rider be careful. Any trike if ridden by an experienced person is safer than a quad but if you try to ride a trike like a bike you'll get into trouble. The way to ride solid rear axle versions (there were some farm trikes with a rear diff) is almost identical to a jet-ski, you lean out on corners rather than in and you don't steer with the front tyre except at really slow speeds, always throttle steer or lean outside and lift the inside rear tyre.

I'll keep my eye out for XL or XR500's around here for you. There was a bike at Morisset swap yesterday, but it wasn't cheap.