Probably one of the reasons why people don't convert is because the way Seraph's behaviors are set up. (an addition to "not much support") MMOE leak source and its behavior system was improved vastly by Phoenix's behavior devs as well as others who shared on MPGH. I could probably set up a tut on making new functions in the Seraph's system but I doubt many would use it, as the MMOE system is "simpler" and "easier".
There's also the issue of adding items. Most pserver devs/owners start off by making and playing around with items, and with the extension/autoId system in addition.xml, it can be more of a challenge for one to understand what's really going on.
Seraphs is probably the best publicly available source to use... for development. It's far more catered towards people with actual brains, than those who blindly follow tutorials and get stuck because that one button was a little below where the tut said it would be.