I'd replace the valve body with a BBA and run a bucket changer. The in-grip air makes for a cleaner profile, but just really isn't practical on the field.
You can get Grey Ghost internals directly from Lapco. I'm 95% sure they are interchangeable. I'll double check for you if you want to go this route. You'll want the bolt, hammer, powertube, and cupseal.
I'm thinking that with battle grips along with the quick change wheel, that would take care of the inconvenience of the in grip 12grams? But you're right, having to take the stock grip panel off is ridiculous.
Would you recommend Grey Ghost guts? Lapco internals seem to be the way to go for reliability and efficiency.
If you want, I have a speed wheel. Maybe it was just the pierce pin on my valve, but it took a lot of force to pierce. More than a bucket changer at least. Battle grips definitely would help. But I'm a left handed jew so they don't work for me.
If you want to buy the speed wheel and possibly the extra stock valve body and pin, I'll give them to you cheap.
Lapco internals are extremely nice.
1. Velocity adjustable bolt
2. Higher flow power tube
3. Lighter hammer
4. Better efficiency (due to 3 and 4)
5. Anti-kink for smoother pump
6. Better cup seal
I can't think of a negative to the Lapco parts except price. But they'll take it from a simple Nelson to a beast of a pump.