Disc front and rim rear is the best of both worlds.

Short answer is no.

From the OP, it sounds as though he is asking, whether the upgrade is worth it. Reasonable question, and by the way, I thought there was a multi page post on this recently... It isn't upgrading as far as I can tell, it is product extension or segmenting. They have the most popular touring frame, what if they miss out on a move to 26 inch wheels, disc brakes, S&S, or maybe gear hubs. Or what if they could simply capture those segments. The fact 26" wheels, discs, and S&S came later doesn't make those things upgrades, it makes them non-core options. The actual classic bike is the LHT, the other stuff is for people with special needs. It's like ultralite camping gear isn't less than a really big tent for car camping, other than on the scale.

Second, while I like the idea that the Disc Trucker is 62% more expensive, and should therefore be at least worth 62% more... That isn't really the calculation. How much in braking worth? Would you spend 62% more to get a bike that could mount brakes, vs one that couldn't? I would. So Disc people come in three flavours: 1) They actually use their bikes in mud etc... where discs have an advantage; 2) They actually believe other brakes don't stop bikes; 3) They are used to buying 4K and up MTBs, etc... and the cost of the Discs is a non-issue. I live in a non-biking part of Toronto, where the bike lanes are like booby traps. But we have a few local bikes stores, and guess what they sell 4k downhill bikes. No mountains in the whole province. But the people with the cash think nothing of spending the 4K.