Give me an exposed linkage any-day. After all they are only toys and I would prefer a working toy over a broken one that looked great all the way up till the point it fluttered. ( As I found out on my first Airworld Cougar )
Not only that on many of the internal linkage set ups I have seen they have had to drop the ATV on the servo so much that the resolution was lost.
Sure if its a huge plane where you can get the horn far enough away from the hinge point to get a good mechanical advantage then great. Otherwise I will happily live with an exposed linkage.
Regards Al