I am not a fan of the mobile site, and never have been. It has many glaring faults, and for that I would tend to vote: drop it like a sack of hammers!
But the real question to ask is an internal one: do you want to expend the engineering resources to maintain a separate mobile site? For the last few years, the answer to that was a resounding "No." Nobody (well, nobody with decision-making power) wanted to commit Slashdot's engineering time to it. The faults, obvious though they were, never got fixed unless they directly interfered with ad revenue.
Now, that's not to say the mobile site provided no value. The outcome of this poll is obvious, so I'd suggest just moving on to the next question to put in front of the community: what does the desktop site do poorly on mobile devices? Yeah, going fully responsive is a start, but it's not the end. The comment slider, for example, just doesn't work with a touch interface. The mobile site handles that much better. So, put up a post asking for input about that, prioritize, and start working your way down the list.
Oh, and if you do end up keeping the mobile site, the #1 fix should be getting rid of the "filtered due to preferences" messages.