By my experience, all 4 yrs of it and my familys 20 yrs of national sidear competition and multiple manx 2 day wins. Fantic 301 , dont laugh, best bike i have had by far learnt my trade on it and wish i still had it.
Montesa 01 excellent general maintenace but nowt else.
Gasgas 04 250 good clutch and exhaust snapping welded up between back and centre box no probs. Gasgas 05 250.
At this point you may wish to get comfy, 3 month old bit of steel gets into engine, dunno how, full rebuild, month later barrel bolt/stud snapped over heated badly in trial wrecked barrel another rebuild, exhaust snapping, water pump siezed twice, thermostats 2 of, clutch master cylinder 2 of, iris chain of standard stretched within 2 trials. dont think i dont maintain bikes anall airbox evry ride, carb 1 a month, greased and lubed kept tidy money no issue if it needed it it got it.
Beta Rev 3 05 got it jan 06 after being used for the manx 2 day only cost me more in chain tensioner rubbers than other parts im now just doing fork seals but i aint gonna cry over that but in all an excellent bike even my mates 05 has been excelllent for him.
I would get another but my kid sis has the 125 4 strk scorpa i love it too so, eagerly, im awaiting the 250 f scorpa after they have ironed out the bugs within a yr or so and when the moths in me wallet have receeded.
I have no beef with the gasser by far the best bike to ride but too expensive to maintain Beta is a different matter.
Hope my waffling could be of assistance to any body purchasing bikes.
If in doubt Beta all the way.