Vintage DD turntables. Are we living dangerously?

Guys, Do what you want.  I'll love you anyway, even Halcro.  By the way, I have never tried jumping off my roof, but I have a fairly strong hypothesis regarding the outcome of doing so and therefore, I won't try it.  (That's an exaggeration of course; I do not regard using an outboard arm pod with the same skepticism and dread that I view the idea of jumping off my roof.  And I totally agree with Halcro, if you do it, use as massive an arm pod as is practical, along with a massive plinth.  If you do it that way, the difference between my preference and Halcro's is minimal.) Anyway, who said I never owned a tt with an outboard arm pod?

Ahh Lewm......the Master of illogical analogies.
Firstly we have the "rowboat in the floating sea" analogy whereby the stable platform of your shelf or rack is likened to the unruly fluid of the sea and the vibrations which uniformly affect the rigid shelf are compared to the multifarious currents and winds acting on a thermal fluid in constant motion.
In this ludicrous juxtaposition.....he then places two separate boats instead of one contiguous raft...
But now Lewm surpasses himself....the results of a person jumping off a roof are well known to be less than happy whereas the results of a person using outboard armpods are so far universally 'happy'. So how goes the analogy....❓

But I also can be somewhat amused with "thought experiments"
The Kenwood L-07D
http://i.imgur.com/VvgdWQi.jpg
which directly connects its platter bearing to its tonearm support via a cast aluminium structure, condemns the fixed mounting dimension of the tonearm to expand and contract with changes in temperature. Over a 10 centigrade degree range, this dimension could possibly change by a few millimetres rendering your carefully executed arm geometry useless.
Furthermore....connecting the arm support directly to the supporting spindle of the platter, inevitably transfers all the vibrations of the revolving platter into the arm base, a design failure of mammoth proportion.
The belief that all turntable designers (and designs) of the past were competent is a demonstrable unfortunate absurdity.

Halcro
Over a 10 centigrade degree range, this dimension could possibly change by a few millimetres rendering your carefully executed arm geometry useless.

This seems a bit far fetched - a piece of aluminium 255mm will only expand by 0.0587mm for a 10 centigrade temperature change according to my calculations. Steel and bronze would be much less than this. Perhaps Halcro, since you design bridges, you could explain your maths.

Halcro
We have been thru the thermal expansion thing already. As I stated some months back, with an aluminium chassis, the change in spindle to arm distance due to delta temp is very small. Dover is correct, it is no where near a "few millimeters"
Of course the shelf on which you place your TT isn't immune to dimensional changes due to temperature. Don't know the material you use, but the change is also likely to be insignificant.

Cheers.

a piece of aluminium 255mm will only expand by 0.0587mm for a 10 centigrade temperature change according to my calculations.

You're correct Dover. Quite small but as record grooves are in the order of microns...I wouldn't be boasting about this concept as you and Lewm do.
The tonearm vibration is a more serious issue however.

BTW...it's not often an architect gets to design a bridge.