I found that the Trumper has more of a soapy quality, like saddle soap; it reminds me of suede, rather than a dirty leather; and it's on the smooth side. Good stuff if it's your style.
IMO, the Truefitt & Hill has less of an outright leathery quality, but its woody notes and other base notes create the suggestion of slight leather...more of a woody leather, if that makes sense. The T&H is darker and deeper than the Trumper, has more dimension. T&H also is spicier, with probably pepper (black?) being the most noticeable spice, but it's only part of the mix, it isn't too loud. Very slight floral note in T&H, very slight, maybe also a very slight moss note. I gave away my Trumper and kept the T&H. Neither progress much, but I'd say the T&H progresses more. Wearing T&H always reminds me of guys in England wearing tweed jackets, hunting, or lounging in the club by the fire, and it has a classic quality, almost of the 1940s. Nice and masculine. You know, I'd forgotten this is a cologne, not an EDT! Great volume for a cologne...I'll have to wear it tomorrow.
Sorry, I haven't tried the SMN, but a few guys here have raved about it.