Firefox plugins auto-update, who's to say the next update won't have something more objectionable?
So Adblock Edge will probably get incompatible with future versions of Firefox, anyway. And if there are security issues in the code, it is rather unlikely that they will get fixed, as fast as in upstream Adblock Plus, if at all.
On the other hand I think it is way less likely that Adblock Plus will add a lot of features that wouldn't be in your interest, in the near future.
Sure it is a change in the ethical background of the product. Adblock Plus isn't a hobby project anymore. It's a business now. That means that it has to be profitable. But on the other hand that also means that there are more resources available. So the product can be properly maintained, further improved, and ported to new platforms.
I think this "ethical failing" (as you call it), isn't more or less serious, or unexpected, than when Google introduced in-app ads in Android. In the case of Adblock Plus, as well in the case of Android, I'm happy that the company behind the product found a way to make the product profitable. So they can maintain and improve the product.
This is analogous to an antivirus vendor taking money from malware authors to avoid detecting the worm of the day, the only difference being that a text ad isn't as likely to frag your computer.
But hey, in both cases, they're getting money to "maintain and improve the product".
Last commit was in May, and besides, the nature of the product (single purpose app) is that it won't have a lot in the way of code changes aside from the odd bug fix. It doesn't need any other feature.
Most of the busywork is being handled in the block lists, and ABP and ABE use the same source (EasyList and others)
