Hey mike
What ever saddle you choose make sure it has side d-rings for your lanyard and of course front d-rings for your lifeline.
I personally use a Buckingham Traverse
http://www.buckinghammfg.com/arborist/Traverse.html
As it has excellent back support for those heavy saws, a hard seat to have a rest, sliding d-rings on the front which helps on limb walks and heaps of rings on the back to hang stuff like pulleys, biners, slings etc.
The version we buy in Australia has double side d-rings so we can clip up our saws with a biner, I actually have a hook jammed between them and my saw has a ring on the strap so I can easily grab and drop saw back on harness "one handed" ... like quick draw... ideal for one handed cut & chuck!
Anyway, where we buy our saddles they have a rope from a roof beam so we can test them for fit and comfort ... but here in Australia we pay $550 for the one I have and the cheapest is about $400 so we spend wisely.