I saw the prototype of the electric SP F5 last week at Accucraft HQ.
As with the prototype, it's a rather plain, utilitarian freight locomotive, with fewer visible appliances and pipes than the S-12 switcher. I'd say that the main attraction of both the prototype and the model is the uncommon 10 driver wheel arrangement, rather than any particular history or aesthetics of the prototype design. The drivers are all flanged, but Cliff said that it still negotiates the 8 foot radius on his test track. The Vanderbilt tender is very nice, but then I really like that style of tender. Cliff said that the most noticeable difference between the F4 and F5 is the clamshell stack extension (F5 with, F4 without).
Cliff said that he has not seen or run the live steam prototype, but expects to have one in time for the National Summer Steamup in Sacamento.