Yes, the flip-out feature is VERY nice -- makes it easy to see the bubble with my left eye while my right eye is lined up behind the scope, even with the level mounted right behind the objective lens, which is much better than in back where it interferes with zooming. Then it lies down when you do not need it, so it doesn't catch on things when carrying.
But the greatest advantage to the FO is that you can adjust the bubble AFTER you have tightened the clamp down on the scope tube. Ones where you have to tighten the clamp down in EXACTLY the right place, allowing for movement caused by the tightening of the screws, are an extreme PAIN to mount. I've had it take me 20 tries to have the bubble be at all centered after the screws are tight. It is also the flip-out feature that enables the FO to be adjustable even after the clamp is tight, so there is another advantage of the flip-out aspect.
Now for the bad news. FO appears to be unreachable. I have a 34mm FO that needs a new part, and FO never answers their phone and does not respond to messages left by phone or through their website. This has been going on for two months.
I have several of their levels and they are clearly the best on the market, but you would think with the prices they get they would have a semblance of CS.