If the current FZ1 is anything like my old '01 R1 motor then Id say hands down go for the FZ.
To date, I recorded the BEST mileage on that R1. On a trip to Loudon from NNJ I recorded an average of 51mpg of mostly backroad riding........so interstate cruising I would imagine could be better. Just be smooth. Plus the FZ would be much more comfortable for a commuter bike..
'12 Tri Explorer
'05 GSXR1k (4Sale)
'00 RC51 (4Sale)