There was a time I started building up a snap on collection because I was apart of the bandwagon and toughed it out paying for tools I couldn't actually afford. That's until I paid way too much for a 10 PC set of the flank drive plus wrenches. I dont like them at all, in fact I do everything I can to avoid using there open ends. I bought them under the impression that they would round off less fasteners then other wrenches. They seem like they round off just about half the fasteners I use them on.
That's just the open ends, the box ends are great. If I could go back, I probably would have at least considered other options first because box ends on wrenches are pretty hard to screw up these days as far as reputable brands go and they didn't exactly invent the wheel with FDP.
Plus I have a problem with losing the 13 and then finding it, just to loose it agian. That wrench is about the only tool that seems to evade any type of organization. Not exactly SO problem though.
I am considering picking up a set of the super combos as well, will probably be a while as its not high on my priorities.
Somethings to consider, that I feel gets lost in context here, is William's isnt apart of Snap On Discount Brands, its apart of Snap On Industrial Brands. Your gonna find things like 40 tooth ratchets, thicker beamed wrenches, sockets without large size stampings, etc because there meant for industrial/manufacturing environments, not professional/repair environments. Not saying that there not worth considering or are obsolete in a professional setting.
As someone stated earlier the beams get thicker as the sizes go up, something to consider which makes me wonder about the head sizes, but at some point your not going to run into as many clearance issues with larger size fastener heads anyways.
You can get the SAE William's wrenches in various colors which I think is a route I'm going to take if I get to it.