I have a Japanese candy cab, Sammy Atomiswave, which is very nice for horizontal games, but definitely not good for vertical shooters (my favourites). As it is really hard to turn the monitor, I've in the process of building myself a vertical shooter bartop (called Space Wars).
And the few times I have played on it to try my Mala and Mame setups were definitely great !
I have only a 15 in monitor, but with a scanline generator like the T-SLG, it looks really amazing !
So your choice of a dedicated arcade machine for vertical playing is more than valid, sir
