I checked the index, and I was really surprised not to find these guys on there, especially since they've been around since 2007 (I even tried the ever-wobbly search at the bottom of the page!).
They're a name I definitely recognise and associate with the first wave of mm epubs, but I've never had an impression of them as big players (though maybe that's because they don't make as many waves as someone like Ellora's Cave). The site looks a bit dated, but I recognise several of the authors, and seven years in business is nothing to be sniffed at.
On the other hand, I'm trying to buy a couple of books to have a look at, and some of the cart links are broken. The majority of the covers aren't exactly calling to me either. Line editors are paid based on a percentage of sales - I don't know about content editors - which helps keeps costs down even if books aren't selling well.
The contract looks fairly standard for an epub - 50% royalties on net where net is defined as total dollar amount received from retailers, three year contract - but I'm actually considering one of the proofreading positions currently up for offer rather than submitting as an author (I don't have any MSs ready to go right now), but I was interested in people's experiences with the press in general.
sorry, link is www.mlrpress.com