Bitstamp changing their client from Bitcoin Core to Bitcoin XT makes absolutely no difference. Only bitcoin miners can vote for BIP 101.
The mining pools have made it very clear with their
coinbase votes that they do not care for BIP 101 at all. Out of the last 1000 blocks mined only one was found using Bitcoin XT.
Bitcoin XT will not be adopted. 75% of bitcoin miners would have to change from Bitcoin Core to Bitcoin XT and the possibility of that happening is nil.
What is a coinbase vote?
There are many member here who could go into more detail for you and probably even correct me on this because I am far from an expert but I'll give it a go.
My understanding is that a "coinbase vote" is a vote from the miners on which BIP (Bitcoin Improvement Proposal) they would like implemented, this current vote is regarding the block size limit.
I think they call it a "coinbase vote" because it is the first input of the first transaction into a new block. (Please correct me if wrong)
If you ever need a bitcoin question answered your first point of call should always be bitcoin wiki, easy if your already on this forum, it's still a work in progress and probably always will be as bitcoin is always changing.
See link
https://wiki.bitcoin.com/index.php?sear ... arch&go=Go