What was originally termed "gasahol", in many cases, is what we now have with E10 ethanol'd fuels. E85 can be up to about 65% ethanol (by definition), from the gas pumps, unless you buy the real E85 race fuel in a drum. That's the difference. As the ethanol percentage increases, so does the need for larger jetting calibrations, which might well mean that current Edelbrocks are calibrated to allow for possibly up to E15 without needing any changes, but certainly E10 will work, as will E0. IF you open the carb for anything, it will possibly void ANY warranty the new carb might have.
The Holleys have always had the "top performance" aura about them. Max horsepower is all that matters to many racers. Nothing wrong with that. I suspect that much of this might come from the extreme tuneability of the Holleys, via thair many "feeds"/"restrictions" in their metering calibrations, which can ALL be changed to address a particular issues in a particular rpm range/situation. Just check their multitude of other things, like accel pump shooters, too.
Back in the later '60s, Holleys (especially, it seems, the OEM Chrysler Holleys) of needing an annual carb "kit" job. Whereas the Carters would last "forever" in comparison. The local Chrysler dealer did not like Holleys, as a result of the Holleys hurting the customer satisfaction of their service dept AND sales dept customers. The dealer would not order a car (i.e., Road Runner) that came with a Holley, but had little choice on the New Yorker 440s and such. The quality and type of the various metering block gaskets/seals was an observed issue, but I heard nothing about similar things from the Chevy or Ford people. Which always made me wonder, back then.
In later times, the OEM-spec Holleys I've had on my cars have been plug 'n play, after installation/adaptations. No leaks, sharp throttle response, etc. Only thing was the placement of the accel pump diaphram at the bottom of the float bowl, where seeps could and did occur. NOT GOOD! One of the reasons I like the Street Demon, other than the fact it seems to be a ThermoQuad revisited in so many respects.
Consider, too, that a "racer" will usually be doing something under the hood every so often to ensure everything is working as desired. So some durability issues with others are not an issue with them. Just part of the deal. Whereas a more normal customer MIGHT raise the hood once a month, if that often, which makes longer-term durability (i.e., no leaks/seeps) much more important. Nice off-idle throttle response always is important, as is part-throttle throttle response. Easier to tune the secondary air door on the AVS/AVS2 than to play with changing secondary springs in any Holley (which also requires purchasing the kit of various springs). Holley does have a more recent "kit" to make changing springs easier to do, though.
Ultimate high-rpm power numbers are one thing. But in daily driving and even in racing, what happens at the lower rpms will influence how things progress toward those high-rpm power numbers. Something that a WOT dyno pull might not reveal. Which is why 2000rpm power/response/torque is important, too. AND can make street driving more enjoyable and easier to do, however often that might happen. By observation, a correctly-tuned Holley, Edelbrock/Carter, or others can work well, either way. Just depends upon how close the particualr carb is to where it needs to be for its application, to start with. That last bit of tuning can be the devlish details where many "trick of the week" changes are recommended, with varying degrees of success.
Just some thoughts and observations,
CBODY67