Personally, I'd rather have a 48/34. Still gives me a nice low gear. You really aren't giving up much with a 48/11 or 48/12 high gear on a road bike. Most of us should be able to pedal around 20mph without ridiculously high RPM's.
Tim
I may go to a 48t outer ring when my 50t wears out but its nice to have diversity
and it really depends on rider strength and elevation changes. I have considered for example a 25/11 in back because I believe it still affords reasonably close ratios and with the 11t in back, offers ample gear inches even with a 48t ring. With a 50/12 however...what I have now, I prefer the 50t for the speeds I descend when racing my friends....I would spin out in 48/12...but not in 48/11. I believe it all comes down to whether you are a spinner or masher, how strong you are and where you ride. The confluence of these elements determines gearing. I do know that a weaker rider or senior rider like myself needs to find the best gearing possible to derive the best performance.
At the end of the day, it maybe 48-38 w/25-11 or 48-36 w/25-11 that works best for me on the relatively flat courses I ride. A senior rider is both aided and cursed by having chainrings closer in size. I really don't want a 48-34 as you suggest because of the 14 tooth difference and constant shifting between chainrings right at the speeds that I ride the most. Also shifting up front is not as comfortable with a large chainring diameter difference. My goal is to have more overlap of gear inches at that speed to prevent constant shifting of the front derailleur. The point is, it is great to have inexpensive chainring options to find that elusive sweet spot which is specific to each rider.