this is always such a heated debate. i think the curved layout is superior for the following reasons:
1. It is more comfortable for extended periods of time
2. It is more aesthetically pleasing...i think it just looks nicer
3. it is more forgiving with minor miscalculations in drilling.
sure, it is not as arcade authentic as a straight layout, but neither are LCD monitors, RGB buttons, glowing trackballs or many of the things people use on their cabinets. Just because these things weren't used on commercial arcade cabinets doesn't mean that they are inferior. If you are going to make something like an arcade cabinet to have in your home, why not customize it the way you like, instead of limiting yourself just because of tradition?
the argument about the curved layout being confusing is a little ridiculous. I have never had anyone walk up to my cabinet and feel confused....even the 3 and 4 year olds that use it have no difficulty at all. maybe if you or your friends are the kind of people who play fighting games competitively, then you may have an issue deviating from the standard, but if that is the case, you wouldn't be here asking this question.
Make a cardboard mockup, test out a few layouts and determine what feels best to you, and screw everyone else, because ultimately it is your cabinet. I can see getting complaints if you put the joysticks on the right of the buttons or something crazy like that, but a curved layout is not going to bother anyone.