According to what I've read, the new runflats are improved over the older runflats with regard to both grip and ride comfort. You are correct that the runflats were a last second thing on the first generation (which is why I went to nonrunflats immediately for summer driving). But the newer generation runflats are supposedly better than the previous generation runflats (and this has been demonstrated on cars other than the MINI as well). Not sure of the difference in the tires, but a less stiff sidewall would certainly help the ride.
It stands to reason that the new runflats would be an improvement--there are significant differences between the different brands of 1st generation runflats, so to say runflats are all the same is an oversimplification.
It'll be interesting to hear from someone who switches from the old runflats to new runflats on a first gen MINI, and also to hear any comparison between the 2nd generation runflats and nonrunflats on either generation car.