You really want the file radius to match that of the frets. I've got a set of three crown files of different widths to match the frets on different necks: http://www.chrisalsopguitar.co.uk/sh..._3_files_TF084. The majority of frets seem to be around 2.5mm in width. I've used the 3mm one on a Fender Tele with really fat wire, but apart from a mandolin which the 2mm came in handy for, I've used the 2.5mm the most.
As has been said, for the price, it's worth a try, but I'd check the width of your frets as that file has a 3mm cut-out and you'd probably benefit from a slightly smaller file.