About the therma rest prolite plus - I am 186cm, the regular is 183cm long.

Is this long enough or is it better to be on the big side?

thanks

When you go with a shorter pad you will lose the length at the foot end of the pad. It is up to you and your comfort level whether or not you will like a shorter pad. Personally I don't mind it, but then I do most of my camping/hiking in the Southeast USA where it is rarely below freezing. The shorter pad will not only not pad your feet, but will expose that end of your body to the colder tent floor. It is really going to completely depend on your own preferences and what type of camping you do.

I prefer to have more comfort at night when sleeping than a little more (if that) comfort when carrying it. It is only 9oz different so for the minimalist that is a lot. I think you will want the larger one. I assume you have a large bag as well which means it will probably hang off a fair amount.

I'm 6'3.5" & the regular @ 72" works great plus the extra weight of the large isn't worth the additional 15 sq in of pad.

If you would like your entire body to be on the pad then you need long. I try to stay a minimalist so i get the short to cut weight, then use my pack to rest my lower legs on.