My observations from looking at LL skiers many seems to have to advanced skis.
(type running Stradas at 15 off @ 28/30mph)
I think is is better to start with a ski close to ones current level and then grow out of that ski.
In most other sports like for example alpine skiing I think one can benefit form a ski above current level.
One can always skid a bit and then make more correct turns through out the run.
Water skiing is brutal in terms of once the pass is started nothing else but god gate and 6 god turns in a row will make a successful pass.
If the ski is sensitive for position the likelihood for a successful pass is rather small and hence once's progress will suffer.
Me for example, I have made at least one rather ok part of each section of the course.
But I cant repeat it during a full pass.
Also, entry level skis are reasonable cheap so one can afford to change a bit more often in the beginning.
Life is too short not to enjoy every day!