I just fixed up my router bench this last week, so got a few thoughts. I use a trend mk2 table because it has an aluminum bed not mdf (stuff gets wet in the UK and mdf is like a sponge and delaminates).
When I'm using it, the bench sits on a workmate, it's not super heavy to move around, and tucks in a corner under a bench when not in use. I don't have any spine issues, so easy to move may be different for you.
I have just upgraded the router that sits under the bench to a trend T11 (dewalt dw625, but with a better fine adjuster), this is a 3000w 1/2" router that just eats wood, previously I had a 1/4" router which would stall easily and made it a very time consuming process. This alps has a 1/4" collet if I want to run smaller bits. There is now a hole in the top of the bench that the fine adjuster drops through, so you can tweak the height by a fraction of a mm. I have removed the micrometer stops for access and removed the springs from the router, so you are only fighting gravity when moving it up.
The adjuster on top makes a big difference, previously I was having to reach underneath and find the adjuster in a really awkward position. If you can afford to, it's definitely easier to have a dedicated router for the bench - it's mildly awkward to remove, and probably 30mins to reassemble the router for plunge work.
While I was at it, I added a magnet to hold the wrench and clips to hold the height adjuster, so they are always to hand.
I've just made 90ft of skirting and architrave with this setup, multiple cuts with multiple bits, and it works really well. Things I would change - add a temporary bit store, a row of holes that bits can drop into while I am changing them. In an ideal world the fence would have a parallel action like my saw bench, where there is a release lever and fine adjuster, rather than pair of clamps, preferably with micrometer adjustment. Not seen any benches with this feature thou.