The overlong Reynolds 531 DB chainstays did them in, in my opinion. Front triangles also felt whippy - don't know if that was a side-effect, or an oddity of the model.
Poorly built, I'll grant it that. Rear brake bridge popped off one side of the seatstay with apparent effort (hardly any braze on it), and both stays have cracks at the seatlug joint (but refuse to snap under intense pressure).
I've been meaning to dump that 728 frame on eBay, knowing quite well someone will buy it, lumpy electroweld on the bridge or not.
I also own a Trek 610, which is essentially 531 mainframe with 4130 stays and fork - I'll never get rid of it for its looks, but I've never cared for its ride either. Stone dead and flat, even though it isn't whippy (but it feels as if it takes some effort to "punch" it - which is why I'll always prefer my two Paramounts and early '90s oversized Columbus EL lugged Guerciotti over the Trek).
I have never ridden any of the 900 series - I'd jump at the chance to do so, but I wonder whether I'd find harmony in the ride. I've become somewhat of a snob when it comes to the responsive liveliness of my machine, and for the most part, if it doesn't perform right, I won't bugger with it.
Incidentally, the 728 was my usual yard-sale hopping machine, with '90s French-touring-type aluminum racks front and back:
After having become royally fed up with the ride, I transfered both racks onto my '84 Raleigh Alyeska (shown as bought - have changed to a double):
The Alyeska does not show the better craftsmanship of the Raleigh USA Taiwanese factory of the era - and the fork is about the worst off-center brazed piece of trash I've ever seen, semi-rectified after 4 hours of fiddling with the blade alignment and grinding the dropout slots - but for a touring bike equipped with crappy Kendas, she gallops off the line as if her rear tire was on fire. She's become my dedicated heavy-hauler, as you might imagine.
Now if only someone sold some brown or dirty-gold fenders to go with it...
Whoops - just realized something I hadn't addressed - got to talking too much about my own bikes then reading your comments . The Trek does NOT feel like French whippyness. Whippy French frames are, indeed, whippy, but they're lively, and will - for the most part - "spring" into a sprint with intense gusto - and enough frame movement for the rider to consider it a suicide mission. The Trek is just dead. Whippy and dead.
Eh, I talk to much. Time to hang it up. I ought to put some of these correspondences on a website...