Haven't done any mods to mine yet, so I'm still running stock with a J&J barrel kit.
My air usage seems to be roughly half what it was with the A5. The gun is definitely quieter and the lack of any serious vibration also increases the shot accuracy, which is a good thing.
The reduction of internal parts also increases the lifespan of the gun without maintenance, ie no tombstone, no visible o-rings, back bolts, springs etc. Love the sealed unit. When you remove the stock from the end of the gun nothing falls out, imagine that?
The only serious cleaning I've done to date if after being on the receiving end of Matt and his Ego, where he's trying to change the color of my gun

To date my only issues are the safe / 3 shot pulls on the full-auto and response modes and the not so robust battery cover on the grip. I'm waiting for APE to release the Phenom Rampage board. They are supposed to be releasing it, but it seems to be taking forever.
D.