30Hz is noticeable but personally I am used to it - in fact I still have a couple of T221s (3840x2400) running at 24Hz. At the time (a couple of years ago) the low refresh rate was an acceptable tradeoff for the high resolution. You can improve things a bit by tweaking the video driver to turn off vsync, which makes the mouse pointer smoother at the expense of some theoretical tearing.
These 4k monitors do run at 60Hz when you drop down to 1920x1080, so you could use that for gaming and have the crisper resolution for work. Whether the lower refresh is acceptable partly depends on what your work is; all I'm saying is don't dismiss it out of hand.
