Bringing this one back up because it is interesting.
TW's have this swivel butt action even when they walk that is very very different from the way paso finos move so I wouldn't think this would be a very good cross or really see a reason to do it. Paso finos now come quite large - there are several that are 16 hands and 15 hands are becoming common and contrary to popular opinion there are many very mellow paso finos out there and these are two of the characteristics common TW's so since they are already in paso finos I can't see the advantage from that direction. As far as TW's are concerned too many have been bred to pace without the big shoes and if there ever is a need to bring back the gait breeding to a paso fino may do it but I suspect there are other gaited breeds that would have an action more similar to a TW with strong gait that might be better.
All the mountain horses, Icelandics, Florida Crackers, and Foxtrotters all cross well with paso finos and several would benefit from the extremely strong gait of the paso fino. Until they identify the gene that causes the connective tissue problem in Peruvians I would avoid any that don't have both sides of their ancestry still alive and sound at 25 years so I can't imagine any breed wanting to go to Peruvians until they solve this problem. It is a wonderful breed but the disease is terrible.
So this doesn't mean to avoid buying a cross TW, paso fino, that is nice, healthy well gaited and so on. It just means I see no reason from either side to do it as their way of going is so different.