The X30 fixed, if you will, three concerns from the 10 and 20:
1) Despite the considerable engineering FUJIFLM expended on the OVF, at the end of the day, as much as I really wanted to like it, it's just not the same view as an old rangefinder, nor quite in the ballpark with the X100 or X-Pro. I was prepared for the parallax from previous rangefinders (and it's just not much of a concern most of the time), but it's just too small for me. I defaulted to shooting from the rear LCD which I hate.
Importing the big-screen EVF from the XT's was a genius stroke, and fabulous to use. It even does the XT trick of rotating the screen readouts when you flip it up on one side for vertical composition.
2) They dumped those matchbook-sized batteries. Despite every energy-saving strategy I could use, I never ever left the house with out two spares and a hot one in the camera. 30's use the same as the X100 and XS-1, and two is all you'll ever need.
3) IF you prefer to use the lenshood / filter adapter, the EVF once and for all eliminates this thing horning into the OVF view. I always prefer to use a hood and a clear protector (I use the bespoke Fuji EBC), and now it's no longer an issue.
I still keep my X10, and the evolution of the 30 over its' two forbears may or may not sit everybody, as the 30 is a bit 'thicker', if you will. All three are serious little cameras that punch above their weight, and judging by how many new compacts are metal-bodied, seem to have extended some influence. When my 10 came out, it was hard to not buy a plastic compact.