About notifications for an invitation to a contest:
It's nice to get a quick look at a project one could be interested in, but I've noticed how such running contests are almost always topped by very high- or highest-rated entries, often as multiple proposals by one or several designers; this discourages me from checking the brief and investing time in pitching something that I think would take first spot in the client's eye, which is pretty much already spoken for.
Although it's true that one could tackle such "topped-off contests" as a good challenge – especially for really interesting projects or when a great idea pops in one's head, whether or not in blind mode – I regularly feel like the pool party's kinda over as I show up with my invitation, so why try to find a drink and start chatting up a group that's already jumping in the water or kissing on the chaise lounges?
My suggestion, if other designers agree, is to release invitations only for contests where the entries' ratings hover around or below 50/100 after a few days or so.
Peace
F.