I have never found a low top speed in any way limiting, in fact many of my cameras, both 35mm and MF folders have prontor shuters with a top speed of 300, and only my Rolleis for MF have the old compur shutters with a top of 500, before that for many years I used a Bronica etrsi with a top speed of 500, these are all between lens shutters,and the great advantage is that you have flash sync at all shutter speed, great if you do any outside portraits or anything else using fill flash, and how often do you need these very fast shutter speeds, even with 400 films, and if you do a lot of landscape the you need slower speeds and more depth of field, with some MF with focal plane shutters you have 1000, I believe the mamiyas go to this, but even with my old pentax's I very rarely used a fast shutter speed, so I wouldn't worry about a faster shutter, just use what you have