I have used the OFK500 quite a lot - I used to work for a company doing solid surface demos, and I used them in the demos for trimming SS edging strips. I liked the trimmer so much I even bought some bits for it so I could use it at home too. Unfortunately when I left I had to hand all the tools back, so I've now got a couple of cutters & no machine to put them on! One day I might get one...
It's a great tool, but as you say is limited by the lack of bits. The only bits available are a straight trimming bit, a 45 chamfer bit, and 5 different roundover bits (2, 3, 4, 5, & 6mm). EDIT: There are also 30 & 60 degree chamfer bits. Sorry about that.
Having said that, what it does do it does extremely well. If you're in a production environment and need a dedicated trimmer for any of these tasks, I wouldn't hesitate to recommend it. It's very easy to set up, easy & ergonomic to use, produces excellent results, and the dust collection is great.
If however you want something that can do more, and want to use standard router cutters then the MFK700 may be better.