Hello & welcome to the world of..... Pht.. you know what i mean...
Try them all if you can, go to your local site or sup-air-field & ask if you can get the feel of one...... But if your on a tight budget then i would suggest the ION...
as has already bin said try them both if you can.
the pmr performs really well stock, but the ion will do to but the ion xe has hundreds of upgrades for it so it can be upgraded axactly as you want it.
the choice me marker is all down to you. I would try a few out before you make your mind up. Personaly i would tell you to get a pmr but i'm not the one who is going to use it.