Tubing for touring - 853 vs 531

[Vicki]

Just looking for opinions/advice here.
Reynolds 853 seems to be a popular choice these days, but I have heard the opinion that - being thinner - it is more prone to damage (i.e. dents, rust).
I'm looking at a bike for off-road touring.
Some people still seem to swear by 531.
I imagine the overall weight difference in a frame wouldn't be all that much anyway?
So is it really worthwhile spending the extra on 853?
(& maybe someone has another suggestion?)

[Roberto]

725 (heat treated and adequate for expedition) or 631 (the "modern" version of 531 and cheaper than 853: no heat treatment). I think the problem with a thin/light frame would be flex under heavy loads.

[rogerzilla]

531 is no longer made, although some builders may have stocks.  631 or 725 are the replacements.

[SPINNERS]

I seem to recall that on a tigged road frame the difference between 631 and 853 is just 20g... and about £300!

[luceberg]

I think Reynolds 525 is very similar to 531, with the same UTS.