I don't think you'd lose the lace affect of the F&F if you did it all garter, but most of the F&F I've seen was a mixture of knit rows and purl rows often 3 rows of knit and 1 of purl and then repeated. It may curl a bit but the afghans I've seen done this way have garter at the ends but not on the sides so maybe it isn't a problem since some of it is garter. I don't know if the cast on, and bind offs will match perfectly. I suppose it depends on which ones you use. I usually use a long tail cast on and a standard bind off, they may not be a perfect match, but they look fine to me.