Hi Sleepy,
You are right about a TL 250 being a Dream Trials bike but the reality is a Nightmare to compete on! Having been down that road, the main problem is when they start to go down it is nigh on impossible to keep them upright. Excellent smooth power for hillclimbs but not very effective brakes and anything but nimble in tight turns. Overwhelming problem is weight, at 100 kg plus (Honda said 99 kg only because they feared tripple digits)!
Having a couple of these in my bike shed, like you I have worked on them with the most common problem being the cam wearing out the head. The ones that I have fixed have been really good in the bottom end so I left them alone and refitted the repaired head.
If "the guy chasing one is the bloke I am thinking of", then he has very deep pockets but short arms!