What I like about Nordtvedt is his strict and cautious scientific approach to all this. He operates with SNP's even more than with STR's. He keeps retesting and refining. His latest surmise for TMRCA of I2a-Din is interesting in that the more he tests and refines the "younger" the subclade gets (not by much but some). I have no idea of how Dorianfinder gets his dates and the "I don't care for N's analysis" approach is of course not particularly persuasive. It would help to have something more precise. It's Nordtvedt who discovered the British Disles older brother to Din. As for Verenic's adaptations cf. the thread here, esp. from posts 113 ff. http://dna-forums.org/index.php?/top..._1#entry221867
Unfortunately we can't get aDNA from the Slavic homeland area because of the cremation ritual. But the possibility of checking exists for some of the Wielbark and Chernyakhiv gravesites, once the Ukrainans get their act together. We could see if there is any I2a1b1 there.