Henry1, the reason most don't do the hammer mod is because it requires disassembly of the trigger group, which can be a daunting task for anyone that's not a tinkerer!! Lots of novices have done their triggers, but it isn't for everyone. Most of those that have done the trigger job, state that it wasn't as bad as they anticipated, it's a pretty simple process if you read Perklo's and Raynor's instructions, doing a hammer mod at the same time would be a piece of cake if you have the basic tools, ie: grinder or dremel, if not, it wouldn't be too easy.
Roudy, a factory extractor has no common parts with the ejector that I can see externally, they appear to be totally different, the underlug is totally different. The extractor appears to be a gear or cog driven mechanism as opposed to the spring driven ejector. I haven't had any motive to tear one apart for examination, and no one else has either.....yet!
Tim