I've been running Mint Maya with Mate for some time now and it's fine on a low-end machine (6-core processor, 2Gb RAM) with 4 RDS servers open, thunderbird mail, half a dozen Kate editor sessions and half a dozen firefox windows with approx average of 8 tabs/window.
Current uptime 54 days so getting a bit sluggish at times with so much permanently open.
Secondary machine (not currently in proper use but lower spec) seems fine and the second-hand Compaq CQ60 laptop, used every evening for audio and video from network and extension Tb drives is more than adequate.
My brother is running a very low spec machine trying to get to grips with linux - again Mint Maya - and gradually succeeding, though it's slow on his setup.
I too gave up on ubuntu - far too bloated and too complicated to use after 10.4. Mint Maya is based on ubuntu 12.04 but seems to contain its excesses.