Is the 15 lb bottle hard to keep at the right pressure with a heater. And other than the size of the bottle is there any other reason not to have one.

 

Not unless its empty.

 

Not with a Cold Fusion 300watt heater

 

Yep, keep atleast 5lbs in the bottle and it will be very easy to hold pressure with a heater.

 

Like has been said already, just don't let it get down below 4-5lbs. It will take a little longer to heat than a 10lb bottle regardless of what heater you use, but the benefit of having the extra volume and holding pressure longer negates the heating time, IMO. Also, the added weight is negligible, and if you are that worried about a little extra weight you can always tune the nitrous system for a little more power, lol.