I ran the 48 IDAs during the intake testing for my book, and they really performed well, but ran out of gas above 550 HP or so. I'd believe that the Berg 58mm carbs would make a lot more top end power than the 48 IDAs, and probably still maintain the midrange torque that made the 48 IDA setup so much better than the other intakes. I looked into buying a set of those Berg carbs after I got done testing the 48 IDAs, but they were really expensive, like $1200 per carb if I recall correctly, so I didn't get them.
By the way, I ran the Weber setup on 4 different engines, with radically different cam profiles, from a fairly mild hydraulic flat tappet to a couple of pretty aggressive solid rollers. I never had any trouble that people warn about with these carbs, i.e. clouds of fuel vapor forming over the tops of the carbs at certain engine speeds. I only ran to 7000 RPM, so maybe this is a higher speed phenomenon. But my general impression is that concerns of this sort are way overblown...