Garbe - it seems in order of quality (low-high), it goes:
Blue / Blue/Orange Super Stainless
Green/Yellow Super Stainless = BlueDiamond Titanium
Super Platinum
So at the current price for the box the BlueDiamonds seem very good value.
I had a quick 2-pass this morning (bit pushed for time) with the BlueDiamond in my red-tip. Initial impressions were good - quite sharp and very little tugging. Better than the stainless certainly, but not quite up to the AstraSP. It also sounded a little "louder" than the stainless if that makes sense - a little more resonant when cutting through the stubble.
Not overly impressed with the shave cream though. I used the same amount on the brush as I would have with the palmolive cream (as a comparison really - I normally use the stick) and face lathered as normal, but only got about half as much lather as the palmolive and it felt less cushioning.
So inital view is 7/10 for the blade, probably 4/10 for the cream. For comparision, I would give the SM Stainless a 5/10 and the Astra a 9/10. Can't comment on longevity yet, but have a gut feeling it's going to be at least a 5-shaver.
I haven't been brave enough to try the shavette yet...
Oh - and they have just dropped the price further, now £6.99 per box. So 2p per blade.