I would thoroughly recommend the mini if you're looking for a small/light set up. I recently sold my PM5 and when posting it out I actually held it and compared it to my mini and the difference is phenomenal. I prefer the feel of the grip and trigger more on my mini too, but thats largely down to personal preference.
What I would recommend is definately trying out both guns. If you're near Brickets Wood as someone mentioned I think, then MK Storm train there regularly and all seem like a great bunch of guys, I'm sure one of them would let you have a hold of a mini if you asked them. With regards to trying an Ultralite PM5, there don't seem to be many around, so you could just use any gun with an UL frame on it and imagine it a bit heavier and bigger