Close but no cigar! LOL
Here's exactly what Bob Jackson says: "Reynolds 725 Chrome moly tubing can be used to build a complete frame or can be used as seat and chainstays to produce either 631 or 853 frames" and then farther down on that page there is a hierarchy of frames, with 631/525 being the bottom of the range, then 631/725, then pure 725, the 853 at the top of the range. If you're going to throw a link at somebody with a big dose of sarcasm, at least read the link! LOL
725 is to 525 what 853 is to 631.
If you don't believe me, give the folks at Mercian a call - they're building me an all-725 frame right now. It's the owner's personal favorite tubing. A bit lighter but more rugged and also a bit more costly than 631. It's closer to 753 than to 631 or (especially) 525.
Another link about it:
http://archive.roadbikereview.com/04/0EFBF1AE.php
and another:
http://www.argoscycles.com/reynolds.htm
And Reynolds own description:
http://www.worldclasscycles.com/reynolds_725.htm
And here - for good measure I'll throw this in since you chose to throw in the sarcasm: Reynolds own strength stats (showing 725 being over 40% stronger than 631) :
Reynolds 631 - cold drawn
UTS: 52 - 58 Tsi, 115 - 130 Ksi,
800 - 900 MPa
Reynolds 725 - heat treated
UTS: 70 - 83 Tsi, 157 - 186 Ksi,
1080 - 1280 MPa
But yeah, if weaker is better I suppose you're right - 631 is WAY better than 725!