I use a DeWalt 618 router with my FMT Pro. It fits the hole pattern in the router plate, so it attaches with screws rather than the rail method, but both ways will work and the rail mounting will fit many brands and models of routers that don't have the right hole parrtern in the plate to match it. I went with the DeWalt 618 router because it was the lightest router that I had that could take 1/2" bits. Other good brands of routers should also be good choices, if they can take 1/2" bits and are light in weight, but if your joints are small a 1 hp 1/4" router would be even lighter. You really don't need a high horsepower router for cutting the small M&T joints. I have yet to try my DeWalt 611 router on my FMT, but I think it will fit and should work very well when doing the smaller M&T work. I never bought a Domino. I just never thought I needed one since I have the FMT and also a DeWalt biscuit joiner, I seem to have all that I need, Biscuits for alignment, and M&T for heavy use strength. An FMT can also cut mortises for floating tenons, if you wish to compete more directly with a Domino, but I think the FMT is more versatile for angled work..
I built a platform of the same height as the FMT to place next to the FMT for a place to sit the router when I wanted it off the FMT base, to minimize lifting efforts.
I justified buying my FMT PRO because I had a job that required over 1,650 M&T joints (making chairs), and couldn't possibly make them efficiently using square drill bits and a table saw tenon jig and then hand fitting each pair. I needed a much better way. I had time before starting that job so I ended up buying and trying several different M&T jigs and I wasn't happy with the results, until I bought the Leigh FMT Pro. The FMT paid for itself several times over with that first job. There is an adjustment on the router plate that lets you fine tune the size of the mortise to the size of the tenon, to make them perfectly fit each other with whatever joint tightness that you are looking for. Then every M&T joint made after that in the same wood will fit exactly the same. There is never a need to go back and fine tune each joint for correct fit, like is necessary with the square drill bit and table saw tenon jig method, as long as you make the cuts correctly with the FMT. Using the same setup to cut both the mortise and the mating tenon also saves a lot of setup time.
During that job I came up with the platform idea and built it after the first day, when I discovered that my shoulder muscles were complaining from all the router lifting I had done the day before..
I also added a 8 X 10" piece of Clear Lexan to the front of the jig by placing a Velcro strip on the jig and the mating Velcro piece on the top edge of the Lexan. This was not to look through (don't bend down to watch the cut through it), but a means of keeping the chips from collecting on the front of me..It's never a good idea to place your eyes in line with a spinning router bit, even though the Lexan might offer some degree of protection.
The vacuum port on the FMT works well, but not when cutting the front side of the tenons. The piece of Lexan helps keep the chips off you, but also helps slightly with the air flow to pull the chips around the tenon and into the vacuum port. If you are cutting long tenons (longer than about 1") the vacuum port will clog quickly. An easy solution is to cut the tenon with two bit depth settings. Shorter depths makes for better cutting accuracy, and no vacuum port clogging. Since you are removing less wood with each pass, making two passes doesn't slow the cutting process significantly, because you can cut each pass faster.
Setup of the FMT takes a bit longer than a Domino, but once right it does a fantastic job, and it does the slight chair angles with ease. When multiple mortising long pieces, Leigh provides some brackets so you can attach lwings on either side of the FMT. These allow you to install stops or marks to make it easy to get accurate spacings between your mortises on long work. You can angle the tenon work in either or both directions very easily.
If you have any questions that I haven't answered, I'm sure that I can help. Although I haven't used my FMT much recently, it has seen a lot of use, and me a lot of experience using it.