I have been using 2Checkout many years so when I found out about 2Checkout Inline option I asked developers from Cs-Cart-Dev to make such payment addon. Now when a customer selects 2Checkout payment method he/she does not leave the site, I suppose it increases numbers if successful transaction.
Talking about the developers from CS-Cart Dev I have to say that I have been working with them for some years and they made for me a lot of custom addons and modification, some of them are quite sophisticated.