I have a Dewalt trim router and a 1/8 up cut spiral bit. The router can take a bushing and the up cut bit makes a very smooth track. The trim router is small enough to make it easy to work with one hand yet big enough to stop it from running away where ever it wants to go. Being able to use a bushing makes it easy to follow a pattern.
Only bad part about a Dremel for inlay is that it does not have enough weight to keep it following the track without a lot of either jigs or patterns or extremely shallow passes to get to depth.
I vote for the router.