As AGMs are "sealed" they should not be subjected to the "equalizing" conditions. Flooded lead acid can take the overcharging conditions that the equalizing subjects them to as they can vent. The AGMs venting are safety valves. Lead acid batteries should be equalized as the plates will build up scale and this reduces capacity. The AGM while "starved" is a lead acid but cannot be equalized. I have had AGMs and now use gel which because of a different electrolyte are so slow to sulfate that you don't even have to think about it.
Before making factually worded statements, as above, please freshen up your knowledge on the subject. Posting incorrect information does not help answer the question posed.
Considering this thread was originally, back in 2006, about Lifeline & Deka/East Penn batteries, and Lifeline says equalizing is okay to do if the batteries are showing diminished capacity, and Deka says no then your broad based statement above is an unreliable choice of presented information.
In a worst case scenario bad information might cause someone with Lifeline batteries to buy new batteries per-maturely, which could be an expensive mistake, before trying and equalizing / conditioning charge.
This is a DIRECT quote from Lifeline:
"Conditioning/Equalizing Charge: 15.5 volts for 8 hours
Conditioning/equalizing should only be done when the battery is showing symptoms of capacity loss. If conditioning/equalizing is necessary, first go through the normal charge cycle. Once the battery is as fully charged as possible, start the conditioning/equalizing charge.
To apply a conditioning charge, first go through the normal charge cycle to bring the battery to full charge. The conditioning charge should then be applied by charging for 8 hours. At 77°F (25°C), the conditioning voltage should be set at 2.58 VPC (15.5 volts for a 12 volt battery). The conditioning voltage at other temperatures is shown in Table 5-2. By using the temperature compensated conditioning voltage, batteries that are not in controlled temperature environments may be conditioned without bringing them to room temperature. If temperature compensation is not available, it is best to bring the battery as close to room temperature as possible before applying the conditioning charge.
For maximum battery life, a battery must be recharged to 100% capacity. Recharging to less than 100% may result in premature battery failure. Lifeline batteries are not covered under warranty if they are not recharged properly. For more information, please refer to our warranty policy."
A more accurate statement would have been to say that some manufacturers say it is okay to equalize AGM's and some or many others prefer that you don't. As always read the manual or check with your manufacturer before equalizing AGM batteries.
Because each manufacturer has specific requirements for their own AGM's, a blanket statement can not be made on the topic of equalizing AGM batteries..
Here is Trojan's statement on equalizing AGM's.
Direct quote from Trojan Battery:
WARNING: Do not equalize gel or AGM batteries.