I've been building and flying for 11 years and actually built my first R/C plane in "83( Goldberg Eaglet 50).
I used Monocoat for several years and I suppose if I stuck with it I would have just as good luck with Ultracote. However, I was covering a 4*60 with Mono flat Olive Drab and had terrible problems with corners, wingtips and getting it to shrink. Then when I ran out while covering a Cub I discovered the shade of O.D. was different. What the heck? I put both rolls side by side and there was definately a difference in shade. Plus, and I don't care what you use,none of the supposedly matching paint matches the associated color of covering.
I decided to switch to Ultracote because it is easier to form around compund curves and wingtips, etc.
It does matter how much experience one has with each type and brand of covering. I have also used Solar Film and Lite Film as well for my small electrics. I still have some Monocoat and would probably use it for different apps including low temp version as well as Tower Cote for my foamy wings.
Everybody has their own preference and experience with different types of coverings, but as was previously stated" there are no bad coverings" well except for the garbage used on cheap BARFs that resemble shelf liner.
I would like to try a fabric covering sometime, but will wait untill I build something appropriate such as a 1/4 scale Cub or WW 1 model. I really feel iron on films look terrible on planes that were originally covered in fabric.
Oh well, back to the building board. jollyroger