It has been my experience that the Russians don't eat much grass. They prefer the broad-leaf weeds and plantlets.
Some of those grasses will grow pretty tall and you will be doing quite a bit of mowing to keep it low enough for your tortoises to eat it. When grass grows tall, to the seed stage, it becomes unpalatable.
Even though Bermuda is a pesky plant, I really do prefer it for my tortoises.