Yes. I'm starting to feel like a broken record, but I'd like to reiterate that you are trying to solve problems using memcached that are better solved by other, existing products. If you want a distributed lock, there are many options-- I use zookeeper for this. If you want transactional nosql, take a look at redis. Etc... These products are just as easy to use (a lot of them even speak memcached protocol) and would fit your needs much better.
-- awl