The only one of those that is a major ebook distributor is fictionwise, they might sell 20-100 copies of an average romance book. However they also might sell 5 or even none if it is an unknown press with poor cover art--and as fictionwise charges $15+50% of cover price that is not a lot of earning power. Anyone can list at fictionwise, even an individual author.
Do you buy ebooks? You need to develop a feeling for the market and whether you book will sell well there. Ebook romance buyers are very aware of publisher and tend to be loyal to those with a track record of putting out quality material.
You need to get an overall picture of the publisher. They are small (less than 20 books), they produce only ebooks, they are less than a month old, they have a self-publishing aspect, their presentation is average to poor. Their sales will be low. Epublishers also have a fairly low survival rate, one opens every month or so, one goes under every two months or so.
Even a good established epress in a hot genre sells maybe about 300 copies in the first year. Only the top 3-4 romance epresses would reach into the 1000's of copies for most titles. The newer ones may not reach double figures. If you book is not romance that is even less predicatble re: sales.
If you go with them realize what you will get, and what you won't. You will be in on the ground floor of a new company in one of the riskiest businesses there is. That is a gamble. The very first thing you should do is find out who these people are, specific names and experience. You might also try reading one of their books.