I experimented with 9 and 18 point supports on my 30" and found that the 9 points noticeably degraded the star test image. The 18 points made the star test image look nicely round to me (and you guys know how critical I am when doing mirror testing). A Sky and Tel article using finite element calcs showed that a 20" was fine with a 9 point (1/20 wavefront), but going to a 30" and 18 points may be worse than 1/20 wave since the deformations go as the 4th power of the diameter divided by the square of the thickness.
As to the 'evenness' of the point positioning design... this has concerned me in some of the point location diagrams that I have seen. Taking a 9 point design and a dividing each of the points into three new points may be better than a 9 point, but it might not be as good as a true 27 point design where each point takes exactly 1/27 of the weight.
I use teflon pads 1" in diameter for my contact points.
I would recommend bubble pack for smaller mirrors in casual observing situations. The bubble pack for a large mirror will need a particularly flat surface to ride on, and will not prevent mirror focus shifts.
Mel Bartels, Eugene, Oregon