Expansion chamber for colder climates or if you like to waste paint, larger barel.
Inexpensive. Accurate. Reliable.
Plastic fore-grip that will surely break apart eventually.
My wife has the R6 Rocket pack from Canadian Tire, and we have a regular R6 with fore-grip as a backup. I use a Piranha BL VF G3 as my regular marker.
She loves the Pirahna because it's pretty light weight, and accurate for her. She hides like the little girl she is, in the back and has finally started showing herself and firing. And taking opponents out now I might add. And she is very heavy on the trigger and she has yet to chop any balls in the chamber. Nor has she had any problems with the market.
With the exception of her marker firing liquid and not re-cocking. However, that was only happening in the fall months (Northern Alberta). I thought of going to anti-siphon bottles, but decided against it. I switched her to a softer spring and tightened the velocity to help with re-cocks when it's cold out. As well, we put on her expansion chamber. She hasn't had a problem with it since.
If you are like me, and would rather play better, than spray more paint, you don't want an electronic marker. So for mechanical, a Pirahna is the way to go. We have three, and love them.
We never have problems with them, and they are very easy to maintain. And very inexpensive.