tbh they will mainly be hpa, much cheaper to run and means that you can be more trigger happy, although I don't know the exact price I was going to get a P* so did some research into them.
The main reason to get this over a P* or whatever would mainly be the feedback, it has a bolt carrier etc so you will get the kick of a gbbr but not limited to 30 round magazines, it seems like a very good idea but I have no idea as to how well it works in practise, although time will tell