There are some registrars with active accts, so it would be interesting to hear some feedback, but there are definitely some registrars who are built specifically for the pupose of catching names. They will know the droptime. They have a robust dropcatching infrastructure of servers and as a result will almost always have the highest success rates, when commpared to other registrars who seem to offer the service simply because they have the ability to. These companies are not setup in any way to be competitive with those who build their core business in dropcatching.
As a consumer, the dropcatching service and providers of such service can be related to almost anything thing else bought or sold. Most of the time, you will spend more to have the best. Beware of those charging the most, however, as they're just as clueless as those offering the service cheapest.