Bloodhound heuristics Level tuning

Hi,

As per what Symantec official arcticles and admin guide says.

Bloodhound heuristics involve a trade-off between higher virus-detection rates and the speed with which Symantec Brightmail Gateway processes mail. Lower heuristic levels may miss more viruses but require less processing power. Higher heuristic levels may catch more viruses but consume more processing power.

What is the risk of trying to change the level from meduim to high?

If it is only about CPU/Memory +  some additional latency seconds that's fine since we are only using about 10% of CPU.

Does any one have an experience of changing that level from default (meduim) to high?

Is there any risk of getting higher level of false positives ?

Please share thoughts