and it seems to me that games with a lot of 3chains (and quads) might be a fun addition as they tend to ask for loosing control at the right point. I am convinced that on a 3x7-grid those would be more possible....
I think when playing 5x5 we get enough situations where we carefully have to decide when to lose control. My suggestions in case of implementation would be to separate the rating systems of respective variants, because it would be a completely different game (well, same goes for 4x4 and similar, but that's possibly just me).
I'd enjoy playing. We could play on the top 3 rows of a 7x7. Just like misère, it'd be an unrated user tournament, and we'd agree to have the correct player resign as soon as the "game" is over.