Not meaning to be "fidgety" at all, but I think I spot a hole in Admiral Benbows math (with all due respect):
28mm minis are (generally) 28mm high to eye (that would make them something between 30 and 32mm to the top of the head).
Re-doing the math and assuming 31mm to the top of the head, the scale would be something in the region of 1/58. Visually, I think that 1/56 fits 28mm much better than 1/64.
Matter of fact, if we assume 32mm heigh (that would be 4mm from eye level to top of head - not outside the realm of possibility at all), the scale would be almost exactly 1/56 (1/56.25 to be exact). That would not impair the fact that (especially with buildings - less so with vehicles) 1/64 can be visually acceptable.
My 2c,
Torradas