Have you tried ack? http://betterthangrep.com/

There are some ack-modes for emacs, too, eg. https://github.com/nschum/full-ack

I haven't, but I don't have a problem with grep, so much as I find there's exactly enough friction with Emacs grep integration to prevent me from ever taking advantage of it.

Presumably the friction involves the fact that you have to tell Emacs the command to run before entering the search you want to do, making sure that you type exactly the find | [e]grep command you want. Then, grep, egrep, perl, and emacs all use different regular expression syntax, so you're never really sure what to type, and you are bound to have to try a few times. (Quiz: how do you search for a literal paren?)

Ack solves this by using Perl regular expressions and a built-in include/exclude list, which is annoying because you'll have to tell Emacs to tell Ack which one to use.

eproject-grep abstracts away having to type any commands or enter an include/exclude list (since the whole point of eproject is to maintain that information), but you'll still have to guess whether it's going to use grep or egrep and type the regular expression right.

multi-occur will use Emacs regular expressions, but only on open buffers.

So I guess the solution is to use eproject to open the correct buffers, and then use multi-occur on them. I will implement that and see if I like it. Perhaps you might too.