Yep, I would say the same goes for the LNWR Jumbo that is preserved in the UK. Not really a good fit for ether operation. One of the exceptions has to be the City of Truro. I wonder how its pulling power compares to the Midland Compound?
The 'City of Truro' and the MR compound were built at roughly the same time (1903-1905), although the MR loco was partly rebuilt around 10 years later. Both ran at a boiler pressure of 200psi and on superheated steam.
City of Truro had 6ft 8.5inch diameter driving wheels and a nominal tractive effort (TE) of 17,800lbf.
MR Compound had 7ft dia wheels and a nominal TE of 23,205lbf.
(As you are probably aware the nominal TE is calculated from various statistics of the loco's physical size. The MR compound undoubtedly has the higher TE as it has three cylinders to City of Truro's two.)
City of Truro is preserved mainly due to being credited with touching 100mph for the first time in the UK in 1904, although the evidence is not strong. The MR Compound is preserved as one of the few examples of compounding being applied to a British locomotive.