We use DT Register for Skate Competition Registration.
I have also used it to conduct member surveys and for join or renew membership on line.
I think both of these uses could be separate products. The advantage to me, as the developer, would be having very similar interfaces (both inside and out) and my competition registration would not be cluttered with custom fields intended for surveys or become a member purposes. We are going to add DT Donate, although I could use DT Register for this purpose, for just the reasons of simplicity.