Hi Dave,
I have a Jet 54A and a Makita 2012NB thicknesser and would recommend both. The separates/combi decision involves compromises either way - yes, it can be annoying having only 6" width on the planer, but on most combis the beds are too short and the fence is aluminium. The Jet combi wasn't around when I was buying mine and I would have considered it (the JPT-310 with 1400mm beds, that is) but it was only £1000 back then. At todays price, the 54A and portable thicknesser are better value IMO.
If you want to see them in the flesh, you are welcome to come and take a look - I'm in East Co. Galway.
Cheers,
Neil