Without explainations this year tested products are just 2:
- ISS Proventia A604 (based on RealSecure)
- Sourcefire IS3000 (based on Snort)
The market leader of this segment, Enterasys Dragon IDS, isn't there.
It's a real pity but the comparison is interesting anyway: it's very complete and it's the only unbiased one available on the market.
As usual you can read it online for free excepted comparative performances tables.
If you need them (I bet you need them) you'll have to buy a PDF or press copy.