Thanks to all those who have pointed out the existence of mountain passes. These were obviously designed in, and I believe, meant to be used since the tops of the ranges have trees, shrubs, etc. There's another climbing route out of the Vale of Ruin directly behind the Draedoth Temple (at least in the 1.4 build which is what I play). I found it by accident with my fourth character build elf ( rogue / fighter / samurai / valkyrie / war Witch) while field testing great-swords out of that wonderful treasure chest on the upper level of Draedoth.
Directly behind the temple a bit to the left of center, there's a ridge-line that drops down to ground level (like most climbing spots). I found it at night by accident and ran the ranges for a while. It's worth the climb and all the fighting to see that big honkin' wall up on top and to the west by moonlight. Went back again much later and thought I imagined it, but found it again. The problem is that there is one of the Vale of Ruin killer holes on each side of the beginning of the ridge at about head level. If you run straight up the ridge, you'll fall into either hole. The trick is to head directly toward the hole on the right, then jog to the left at the last moment and you'll run up the ridge line. Normal left/right zig-zagging works from there. You come out directly above the elf-lands campfire, which is also a climbing spot so this is a true pass that would let you cross from elf-lands to the temple, grab a few choice goodies, and retreat back to the elf-lands without a moon-stone. Providing you survive what will attack you on the Vale-of-Ruins side, of course.
The mountain passes change the whole flow of the game for me. I had an old save of a rogue female elf right before she entered the sewers. I had her go back and prowl around the temple ruins and two shacks of the beginning area using hit-and-run tactics, ambushing from the porches, etc. to work her way up to near 5th level. Then she climbed the pass out of the beginning area, survived the attacks on top and dropped down to the south gate of Fargrove with enough loot and experience to buy some modest armor and the light Kris Blade (3-7 damage) from the armory, and then baited the troll and helped the guards kill it to gain more experience points. Now she's ready to do the normal Fargrove quests to get the gates to open, then head west and north to the south of Devils Marsh mountain pass and drop back down into the beginning area and explore the sewers on her terms, rather than those of the goblins.
While I know it had bad press and lots of bugs in the beginning, with the 1.4 patch at least, the more I play the game and try different approaches, the better it gets.