Matthew,

Never had any issues with the internal system on my Blade or Falcon and I travel a lot (I try to minimize the capzised though :-) ).

Since 2 years we are using the nicest system from a usage point of view on the Falcon I find.
There is an external 1/16 downhaul as you can find on many F18's, but it comes with spinlocks and is easy to remove from the mast (meaning you can splice it in the front beam).
Compared to most other cunningsystems this one is always easy to cleat or uncleat (even with high tension on it) and does not undo itself when taking it out on your trapeze!

I can post some pics if you like.

Gill