Because of that you are mainly stuck with same grips and same mainspring.
Not really. Bobtail MSHes use an officer's model mainspring which comes in six different weights from Wolff. You can also modify or order grips for a bobtail. Your selection of parts specific to a bobtail would be a heck of a lot better than it is for my widebody. Try finding nice walnut grips for a P14 (and let me know if you do).
I think it's a neat idea, bobtailing, but I don't see much benefit. IME, the biggest issue in concealment is the length and width of the grip. Bobtailing just cuts off one of the corners. It feels a little funny in my hand, but it didn't affect shooting. Grip length in my hand is more important on the front strap than the MSH.
I think you'd do fine with a bobtail if it feels good in your hand.