I have mixed feelings about the proposal. I think there are strong arguments to be made for having a 'large science meeting' for TCS that is not exclusive in the way that STOC/FOCS are, so I like the idea of SIGACT being behind a conference of this sort. I think it is bad for the community that, more and more, the only attendees at STOC/FOCS are people with a paper. But I am concerned about converting STOC itself into this conference. Perceptions are slow to change so if STOC turned into the kind of conference that is outlined -- where papers are submitted and accepted rather nonselectively -- then I think there would be confusion about whether papers are "old" STOC papers (I could see people calling them "real" STOC papers, unfortunately) or "new" STOC papers. This confusion would probably come up many times in evaluations, letters, etc. I also worry that halving the number of (let me say it) "real" STOC/FOCS papers is not a good thing in terms of growing the field. I haven't thought this through very carefully, but maybe a possibility would be to have a large nonselective flagship conference annually in conjunction with STOC (which would retain its usual role and name). This could have a couple of pluses: there would be a built-in 'seed audience' of 'key players' at the new conference (the STOC attendees), and it could help to grow STOC's visibility since it would be right there with the larger meeting (much like having STOC at FCRC sometimes does now).