I haven't dealt with either of them. They both look amateur, and I don't think they have access to conventional distribution systems.
The erotica site looks livelier and more substantial. That's probably because it's harder to get erotica published via conventional means, so a better grade of work winds up getting published by these outfits. Erotica also speaks to more tightly focused audiences -- no naughty book ever written appeals to everyone, but to readers who are part of a book's target audience, it speaks loud and clear, and there's not an overwhelming amount of competition from mainstream publishing -- so it's easier to sell erotica online than most other kinds of fiction.
The absence of high-volume sales isn't surprising. Subcategories of erotica tend to be exclusionary. Readers are fascinated by books that speak to their own particular taste, but tend to perceive works that speak to other tastes as boring, offputting, or downright distasteful. Diluting the erotic components by adding plot and characterization can broaden the sales appeal, but one rarely sees a genuinely broad-spectrum naughty book.
The order of reply has nothing to do with the quality of the press. Some presses keep up with their slush piles better than others which means faster responses.
Most ebook publishers do not accept or consider simultaneous submissions because, typically, responses are made in about two months or less. This negates the need for simultaneous submissions as the time between submission and acceptance/rejection is far shorter than it is for larger publishing houses where waits can be a year or longer.
In my experience there is a pretty good correspondance between response time and sales volume, at least within the same genre. There are exceptions of course, but I bet you with hear from NCP before EC.