I had a ton of house rules for my campaigns (including many of the Dragon Magazine/Forgotten Realms dragon enhancements you mention), but I was able to toss most of them out with the arrival of 3rd Edition, because they were now included in the "official" core rules.

It was rather scary, actually. I had created these new character classes (like the sorceror), systems of magic, fighting skills, multi-class character development, etc. for the express purpose of developing characters as we saw fit, only to find it all replicated almost exactly in the new rulebooks.

My 30-page variant rulebook was reduced to a handful of footnotes overnight.

And that's a cool pic of the ankheg, _dodger. Not quite as spiky/segmented as 3rd-Edition, but I suspect it would be very intimidating in Poser, regardless.