The 4rt has a nice feel to it very sturdy but it is heavy I think personally that the smooth power and extra torque makes up for this extra waight seems to provide more grip than a 2 stroke and the build quality is second to none and the technology on the 4rt is very advanced for trials but there are some new 2 stroke bikes coming on the Market (ossa, greves) that should lift the bar on 2 stroke bikes might be worth waiting to try one of them.
I personally have never had any thing other than a montesa 1st a 315r and now a 4rt I would not have any other make and never a 2 stroke again the 4 stroke is more expensive but well worth it.
Good luck and try out as meany as possible