Leon,

   I don't have a dog in this fight, but let me share what I
see as a practical benefit - as opposed to a theoretical one
- of going to the TES outer O-ring.

   You wrote:
 
> I'm also curious as to just when and why would you be considering rebuilding your engine (so you can re-use the TES O rings). seeing that if an engine rebuild is done peroperly in the first place,  they seem to last for up to 20 years and 500,000 km if looked after ...

   I'm a relative newbie to the rotary world, so I'm
building from a base that's pretty much all "book knowlege".  
Previous experience in other fields leads me to expect that
I won't necessarily get it right the first time, and that I
will probably have to tear it down and re-do the porting a
time or two, before I get the 200 honest mustangs that Gary
is building my prop for.

   I'm building on a shoestring (otherwise, I'd probably just pay the tab for a Turrentine engine.)  So the idea that
I might be able to re-use those O-rings a few times is very
attractive to me.  

   Beyond that, I couldn't agree with you more.

Regards,                    
Dale R.                              (___
COZY MkIV-R13B #1254          |----==(___)==----|    
Ch's 4, 5, 9, 16 & 23 in progress   o/ | \o