Try it and see what happens in your configuration.
I reduced rejects from 6% to 2% by doing this. I lost 1% hash, but the reduction in rejects more than made up for this.

Going to Intensity 20 adds several seconds of latency to share processing. On very fast alt coins, this makes a big difference. People talk about choosing the correct server due to latency, etc. Intensity is the elephant in the room, adding more latency than anything else you could do.

Changing the intensity made more difference than moving my miners from a 28 kbps GPRS connection to a 60 Mbps fiber connection.

The latency was never much of a problem as I used to mine LTC with its long block time and stable difficulty period. The latency became much more noticable on middlecoin, because it spends a lot of time mining 30 or 60 second coins.