Caspian237 is right, Boeing's protest is not about the merits of each tanker (as both would be excellent tankers), this is about making last minute changes to the RFP (request for proposal) in favor of the NG/EADS aircraft!!
First, the "frankentanker" argument is pure garbage. Doesn't the A330MRTT use the A340 wing? Each airframer is assembling airframe components to produce the tanker they feel best meets the mission requirements, period.
This also isn't about the fact that the KC30 is a larger tanker than the KC767, of course it's freak'n larger. But larger is not always better, as it depends on the mission. This is why in all the aviation universe there are both larger and smaller aircraft, as each have their place. Look at the current USAF mix of tankers, 500 plus KC-135s, and less than 60 KC-10A Extenders. One is medium sized, the other is large. I note that most airlines have more smaller aircraft than larger aircraft, and I note that DOD has more smaller cargo transports than larger cargo transports. This mix of more smaller than larger aircraft is common in aviation, as you all know.
This RFP was originally drafted to replace the KC135 fleet (the medium sized tanker, not the larger tanker). Boeing's complaint is that the RFP was changed at the last minute to favor the larger KC30, which WAS NOT the original requirement. If it had been the original requirement, Boeing would have offered a 777 based tanker instead. Boeing further states that the complex evaluation formula, was both created for the USAF and altered at the last minute by ANOTHER DIVISION of Northrop Grumman, thus creating a direct conflict of interest favoring the larger KC30 at the last minute.
Again, this is not about which aircraft has better merit as a tanker, they both have merit. This is about changing the requirements at the last minute, all other arguments are total BS at this point. Imagine your outrage if you worked many many months and did your best to meet the exact requirements as laid out in an RFP, only to have your competition change those requirements right before the decision is made, in favor of their offering!!!
That's what this is about.