I have no experience with the SuperTuck. But I do with the Walther P99AS.
It is just slightly larger in grip length than my G19.

It is a great gun, probably one of my best, but heck I say that about all my guns.
I will say that I like the decocker on the slide and the fact that every time you pull the trigger it actuates the striker, it is the only striker fired pistol I know of ( though there may be other ) that is like a DA/SA pistol. Rack a round in to the camber and the pull is very easy, if it does not fire you can pull the trigger again and it will strike the primmer again. Not just once like a Taurus, but every time you pull the trigger.
The second pull is only slightly heavier than the first. Really great gun.

i made the decision to go with the P99c with the grip extender. the only differences are the 3.5inch barrel vs 4inch and 10rd vs 15/16rd mags. with daily carry, my opinion is you have to worry about the grip poking out or printing under clothing. the barrel is pointed downward along the leg so length isnt an issue. so with the compact version, you can use either 10 or 15/16rd mags.

here is my P99c with grip extender and streamlight TLR3

I prev had a P99 and a P99c. I also had one of those grip extensions. I found that for some strange reason, the grip seemed to twist in my hand with the mag extension piece. I shot better with just the 15 round mag sticking out of the P99c.

But, I did shoot the P99c more accurately at longer distances than the P99c. My groups were tighter too.

However, I also carry a Beretta 92FS concealed. So, I'd say - get the regular P99.

If you carry it IWB at 3pm, it will conceal fine.