Here is something that was shared by an engineer at a leading charger manufacturer. And, this may help Optima owners.
An AGM, such as the Optima, would like to see a higher voltage over a longer period of time in order to fully charge. This is accomplished by a quality multistage marine charger as it delivers a higher voltage than an alternator but at minimal current as to not damage the battery.
Also, an Optima representative actually recommended a Ctek charger as they liked its use of pulse technology. The 7 amp unit is a perfect match for a Group 34 Blue Top and even a size up. The 3 amp model is fine for the starting battery.
So what I gather from a collection of sources is this.
If you are using AGMs then use a dual bank charger of adequate sophistication and capacity. But if you're not going to make the investment and be very disciplined in your charging routine then you are better off sticking with standard flooded batteries. A flooded battery is more tolerant in some respects and represents a lower investment.