Aside from the cutoff piece warping, this is a great way to make profiles like that and a bit safer. It's also nice when you can just rip the part to size.
I have problems cutting the grooves first since inevitably my router bit bearing will drop into the grove if I can't use the fence (curves). Seems the bit I use will always have a bearing thinner than the kerf 8^P
I know what you mean. My bearing is 3/16 and rode half in the kerf. I didn't do a full 1/4 round. For these, I also could have cut the profile first, but wanted more surface to ride on the table. It was a consideration.