This is basically it right here:
[XT Supporters] believe that Bitcoin should be able to handle all the transactions on planet earth, from everyones daily coffee purchase, to everyones house purchase, to how Google cars should be paid for their services. On the other hand, you have those who believe Bitcoins core value is the fact that it is a hedge against fiat currencies, and by extension, governments (in the case they decide to infringe upon your liberties). Bitcoin CANNOT be both. Its just not possible.
The above is the real argument, everything else is FUD and just craziness.
Do we want it to handle all world daily transactions,
or do we want protection from current monetary systems and government involvement?