That was dont use a drop IF YOU CAN HELP IT...its a fact that using a drop, can make it more uncomfortable and a less tight profile. It wasn't a cust a dried statement...the individual may not be aware that not using a drop is an option!
While I doubt it would make anyone's penis longer, particularily female players, a more stable platform could improve accuracy and could make it easier to walk the trigger (did for me) so, yes a few more Bps might be possible.
Depending what reg you are using, if it's a MaxFlow, you can get special drop's designed to fit the MaxFlow dovetail, so you dont need the rail that they come with, from NewDesignz. It's usually the guages on the reg that get in the way, or the neck of the bottle, so a deeper drop would be required.
Impy's are quite tall markers anyway, so the more the drop, the taller the overall height becomes and the less tight you can get.