I have built a few planes from both companies. In general, WM planes are better designed and will build lighter than CMPro. However, CMPro seems to be much more comfortable with composite construction, which allows them to offer more warbirds and aerobats with very true to scale contoured fuselages.

Instructions/manuals are about the same - pictograms with few written words. I actually prefer this style of manuals mostly because I'm too lazy to read text and don't like wordy instructions. Most manuals repeat the same old drill over and over anyhow. If you have put together a few ARFs, most of cautions/warnings/explanations will seem old spiel. However, a lot of people feel the exact opposites - preferring more written words.

Included hardware are about the same, about average of the ARF industry.

I wouldn't hesitate to buy an airplane I like from either company, though like just about any ARF manufacturer, there are always the good, the bad and the ugly in every product line.