I own an S11 and I can say it's THE machine for the kind of shop you have.
I've owned numerous lathes and mills and everytime I bought a new mill or lathe, it was because it was a better / newer machine than the one it was supposed to replace.
And indeed, most of the time, it turned out to be better.
But never did a "new" lathe or mill give me the feeling that I had something totally different as the S11 did over the previous T&C grinders I had in the past.
An experienced grinder hand will do almost anything with any machine, but the S11 is awesome for its ease of use and speed. (for a T&C grinder, that is).
It is incredibly well thought out.
It's very particular layout with the "T" shaped base, the fact that all the members are on rollers with quick locking levers, the reasonable weight of the various accessories and the motorized (up/down) wheelhead make for a very comfortable and quick use. That makes a world of difference over othre machines imho.
Don't get me wrong : tool grinding is SLOW and an art that is very difficult to master.
It requires an incredible number of operations even for simple cutters, and numerous different setups.
An S11 won't make it quick nor easy, but it will make it as quick and easy
as possible for a manual machine.
If you haven't done it yet, check out that video :
It will give you a pretty good idea of what the machine is capable of, and its ease of operation (don't bee fooled by Mr Muscle moving the machine members as if the movie had been shot on the moon because they are slightly heavier than the video would suggest, but only slightly).
Judging from the litterature I read and observing the machines, I think the S11 is much more versatile than a Monoset, a Christen AU150 or a Hahn & Kolb WS54 (all of those machines featuring a built-in spiral grinding device).
It's sole competitor may be the latest manual Saacke, but the latter appears to be an S11 clone more or less.
If you can afford it (make sure it has all the accessories you'll need because otherwise, you may have to spend yet a fair amount of cash to get it where you want), go for it !