Bob,

My wife bought me a dual-bevel DeWalt for Christmas last year. So far, I've mostly only used it as a chop-saw for dimensional framing lumber (not exactly precision trim work), but I've been happy with it so far, and don't see anything that would be deficient for trim work except that it may benefit from a taller fence for tall crown molding work. I think the stock fence will handle 5-3/4" high crown though.

I don't know if anyone really NEEDS a dual-bevel saw, but I will say that it is nice if you have limited space that makes it difficult to flip your lumber end-for-end. Instead of flipping your lumber, you just change the setup of the saw and you're ready to rock. This is especially useful for doing trim work (very long stock) where you want to try to keep the stock as long as the longest dimension of your room, making it impossible to flip end-for-end without taking it outside (no fun in the winter). If you have plenty of room where you plan to do your cutting, you can fairly easily trade convenience for dollars and go with the single-bevel saw, that's your call. Since my saw is going to eventually find it's home in my future cabinet workshop, we decided that we would take the hit now for future utility.

I wouldn't chuck the manual saw out though, there are definitely times when the old hand-saw is still the most convenient saw for the job. It is a lot lighter and easier to set up for small jobs.

Whatever you do, get yourself a good saw stand and some stands to support the stock while you cut. I have a roller stand which works pretty nice for supporting the stock.

Happy cutting!
Larry