I wouldn't say its thousands to get used to a C172. Although to be fair landing G-BCYR is still a bit of a challenge after 200 hours in the old girl but I think that is an airframe issue not a type. I don't know any other C172 that makes "airwolf" noises when you flare to land.
What you learn flying a tommy is just as relevant to flying a turbo prop as it is to a SEP. I use exactly the same method I teach in the tommy as I do when doing a session on stalls in the sim for a LPC. And actually my aircraft type apart from control loads has remarkably similar characteristics in the stall.
I still reckon that a PPL on a PA38 is a firm foundation to the rest of your career be it PPL or CPL. Actually thats bollocks its all about the instructor. If you have a instructor that hates them or scared of them you ain't going to get taught properly in them. So you will loose 50% of what you could gain from learning in them.