Actually, no, they've been having huge problems with it; with nodes crashing all over the place and such. Of course: Bitcoin Core nodes on testnet are unaffected: They're just ignoring the XT chain entirely, banning those peers, and continuing on as if they didn't exist.
We did have some trouble with a couple of features that I was testing out in parallel -- namely, Mike Hearn's alpha thin blocks patch (which works 99% of the time, unfortunately) and the BIP65 + low-S patch for BitcoinXT (which has some problems when heavily reorging and removing a block that contains either a high-S transaction or an invalid OP_CLTV instruction). However, these are unrelated to BIP101 and large blocks. So far, as far as I know, we have not had any crashes or problems due to large blocks themselves.
it is not about crashes..