Many of us use everyday (me included, typing papers of +60 pages on monthly basis). There are still some rugged edges in the GUI but is certainly not alpha quality software. The Qt interface have been there since at least 2009 and nowadays we have one or two nasty bugs which we plan to address in the following months but nothing serious. As you can see from these videos (here https://www.youtube.com/playlist?list=PLjXdYclFpynD0ufg_pp-5... ) all is quite stable. Unfortunately TeXmacs stress many corners of the Qt/Mac port and we need to go around bugs there constantly. If you experience more reproductible crashes then would be good to know, either show up in the mailing list or file a bug report in Savannah. If nobody complains we cannot fix them :)