I agree, it would have done them good to keep him. although on "the civil surface" Steve Hillage guests on a couple tracks.
If you want to hear what they sounded like with steve hillage, early on, try and find the cd "Arzachel", which is basically Uriel(egg w/steve hillage). Its more of a psychadelic album than the egg stuff:
YouTube - Arzachel - Clean Innocent Fun (1969)
YouTube - Arzachel - Queen St. Gang
YouTube - Arzachel - Leg (1969)
and The Metronomical Society is really good, but the sound quality could have been a bit better on some of the songs.