I have been happy with my Nicko Sew analog servo and they have provided great service for a post-bed I purchased from them. I am also happy with my other knock off analog servo from Ralphs Power Sew in denver. I recommend a local shop if you can find one, Nicko Sew was great to work with over the phone.
Make sure your pulley is small enough, that can really help out. You can always add a speed reducer if you want it to crawl. I am not partial to the clutches they take a bit getting used to.