The Focomat 2c enlarger isn’t exactly small, but certainly narrower than your current 4x5 enlarger.
Contrary to popular opinion they do wear a little here and there. The auto focus cam can and does wear after heavy industrial use, I have seen this wear myself in an industrial darkroom; but that’s about it.
As many of these enlargers were purchased for industrial use, this is one of the few bits that I know can wear out on this enlarger. Even if the auto focus cam and/or associated parts are worn, the enlarger is still perfectly usable; one just focuses by hand as per normal.
They usually came with a 60mm (I think) 35mm lens and a 100mm lens fitted to a quick change turret; brilliant piece of engineering. As a result 35mm enlarging usually required a high (ish) head height, which isn’t a problem as the head can go up very high.
Check that the lenses do not have any issues, if they do, then fitting other types of lenses could be problematic as far as auto focus goes.
If the one you are after has a diffused Ilford multigrade head, I would be running to get it; that combination is simply marvellous.