I thought for certain that subbing drg would allow the wyvern to be summoned after the drg 2hr fix. SE wants people to be more versatile and creative when choosing subjobs, but make only a handful worthwhile. Sub drg should definately get to summon the wyvern.
Drg/Rdm and Drg/Whm are incredible at soloing starting at around lvl60. There's a Pimp Drg on my server who can outsolo most other jobs. I think he uses both /whm and /rdm in different situations, but I don't know his exact reasons. Jumps allow a Drg to avoid large spike damage from tp skills and and high end magic.

Drk is definately a contender endgame with absorb-tp and the new merits for it. There are 3 main reasons that Drk's have been ignored(for the most part) endgame. One is that spike damage incurs too much hate and with their low def/vit they're an mp-sink for whms. The other reason is that other jobs hate to sc with drk because they're slow gaining tp, but now that's not so much of a problem. The third reason is that mainly ignorant noobs played drk in the past and ruined its reputation. No absorb spell and no amount of merits will ever fix the third problem, so drks will always be trying to prove themselves against that old stigma, but at least now the intelligent drks out there have less to fight against. With drk though, be ready for the first 30 lvls or so to be pretty annoying. Unless you're going to use sushi, your acc is going to be horrible and you're not going to see the major damage that you see at later levels.

Also, if you start to get frustrated, take a break but don't give up on your main job. Constantly changing jobs will keep you from getting into the funnest and most rewarding parts of the game.