I know that TEP has been going on and on about this business of greens "coming alive" at those speeds when there's a lot of contour to the greens, but I just wanted to add my comments to that and say that he's not alone.
I had privately mailed him early this spring asking about his experiences with A4 bent since my club had closed last August for this regrassing and was due to open in May, and his club had regrassed with A4 bent the year before so he had already seen how things turned out firsthand. He told me that by the end of the first season the greens would already be better than they had ever been before, and based on some other clubs in the area that had done this a year before his the second year they'd only get better and better.
I've definitely seen that this year, and the effect on play has been remarkable this year since previously our greens would work something like this:
April 1 typical opening day
April - greens still waking up from dormancy
early May - aeration with 1/2" cores to remove thatch
rest of May - greens recovering from aeration
first half of June - greens great, very fast up to 10.5
mid June to end of August - heat & humidity creates stress on greens so they are only sped up for tournaments, rest of time run about 9
first few weeks of September - greens great, very fast
around first day of fall, more 1/2" core aeration
late Sept to mid October - greens recovering from aeration
rest of season - greens good but all the leaves blowing onto the greens are your big problem
When they first opened with the new greens in mid May they were probably about as good as they would usually be at that time of the year, but have been getting better and better all season. Around the end of June when they'd usually be cutting them higher and overwatering to keep them alive, they've been staying fast and firm -- if they were watering them at all during the dry periods this year it was certainly never evident.
The amazing thing is that they just keep putting truer and truer as the season goes on! Between that and fixing a long time stupidity in my putting stroke my confidence and results with my putter have improved by a large margin this year, and that's carried over onto other courses I've played. Plus playing them when they've been running fast all summer has been a real treat in terms of forcing some real imagination with the short game and putting thanks to my incredibly awful iron play this season.
Certainly the approval isn't 100%, there are some who complain about "unfairness", but when I've played with a few people saying that "its impossible to stop a ball by the hole from here" I'll drop one after we putt out and show them how its done. They might think it is ridiculous that a 20 foot putt should take 25 seconds to get to the hole, and its luck that it actually stops somewhere near it, but I think it shows you shouldn't be there if you can't handle the putt. For some reason I take such a delight in the look on people's faces when I aim for a 20 foot break on a 15 foot putt I almost want to seek out such spots just for their expression when I'm lining it up!