A few thoughts-
Since most of us are going to spend $40+ on shipping anyway, I wouldn't mind spending a little bit more for a nicer SPS.
I would take down as many parameters as possible, but make them all optional. The more data we can gather, the better.
That said, there is no way that we have a sample size large enough to make a statistically valid determination on coral growth, but it's still better than what we had before.
Water displacement is probably the best option for determining growth. I like the idea of sending the colony to one person who will frag it, mount it (on discs?), let it heal for a couple of weeks and then determine the size of the frags being sent to each person. Graduated cyclinders are very accurate and, as long as we run this long enough, we can overcome any small inaccuracy with growth to make it negligible.
CJ