I spend, conservatively, 300-400 hours a year behind my 15s. I, as well as several of my buddies tried the pistol grip heads. The original Bogen ones were junk. The spring would let them creep and required constant readjustment. The Outdoorsman one is better with the little finger hook thing but still not a good choice for grid glassing for unseen animals. I also have gone through two of the Swarovski adapters. They too loosen over time and cost more than the better Outdoorsman adapter. They are also heavier. Guys that don't glass off tripods a lot may not notice these thing but I literally spend day after day behind them.
I have a tripod that I can stand up behind. I do a lot of glassing this way. Sometimes you can't see very good on flat ground. I also do a lot of glassing from the top of my truck and this is where you have to stand as well. My tripod is an EL Carmagni model or something.
The guys at the Outdoorsman tried to tell me that the carbon fiber tripods set up bad vibrations when glassing. I have never observed this so I am glad I have the one I do.
A lot of guys like the Jim White head. I personally do not. It is very well built and serviceable but pales compared to the Manfrotto fluid heads. I had a little Bogen ball head for years and even it was better.
Other than the cheap, junky pan heads that come in some combos, the pistol grip ones look cool but are not much fun to use day in and day out and are the worst possible choice.
If you think the stuff you need to use the 15x56s is expensive, you should see what it costs to outfit a Kowa Highlander- the Cadillac of big eyes!
