A BIG fault as anyone could get the domain, and refund the money on PayPal saying that they didn't receive the goods or services. Maybe it's your preference to use DomainSite, not saying they are a bad company, infact I have a couple domains with them, but I like to feel secure with the sites I'm transferring.
IMO Godaddy is the best for domains because a majority of webmasters already have an account. Generally hosting is not included in transfer but 3ix.org do hosting for $1 a month which is fine for small sites. I have some helpful articles/advice check out my sig.
Dynadot.com is something I use for the last year or so... and www.asmallorange.com for hosting Get $5 off with my coupon "painttheinternet"
i use godaddy and pushing sites is very easy as long as the person has an account. what type of sites are you planning on flipping