A pattern I noticed in testing was that Cyren was good at finding cases of unique spam or spam that the other checks didn't find. It missed some of the most obvious cases of spam that thankfully the other checks were catching. This might be the "zero hour" behavior of Cyren, good at catching *new* stuff. We did some testing and noticed MS and Cyren trading blows on what they were finding. Plenty of cases where each found spam that the other didn't. I believe we have some Cyren stuff being announced soon that Tim teased in another thread, so keep your eyes out for that.
As far as delivery delay goes, it should have no impact on the checks. It's there to give the file a chance to sit on the disk before we touch it with checks giving the chance for AV's and the OS to touch the file in whatever ways it wants. We do the delay and nothing else and then afterwards each check is done one at a time.

It's easy to say just buy both, but based on the research I did, having both MS and Cyren does indeed provide a bigger net that catches more than each individually.

We never had good lucky with Cyren, overall, I'd give it a 4/10. The stuff it did catch was stuff RBLs would have knocked down on their own, other stuff it would classify as spam that was not, then it would not catch blatant spam emails that RBLs were not yet identify the source as spam.

The same with Sniffer, many FP, didnt seem really any better or worse than using some of the higher quality RBL lists to score on source IPs. Sniffer I dont think really any any "intelligence" behind it, it appears. We also tried it directly integrated into our Postfix gateways just to see if maybe it was any better not attached to SM and the results were the same.

We have a customer who uses Cyren at the MX level, and Cyren processes all their mail directly, apparently it has more features than what the SM integration offers and that customer has told us they havent been very impressed over the last 2 years with them.

Maybe the announcement from Tim regarding Cyren brings some better news?