Having CANBUS compatibility may be of no special value, however, from my reading, having a charger that is Gel battery compatible can be very worthwhile.
My understanding is this: A gel battery can be messed up by feeding it too high a voltage when recharging it. And its max safe voltage is lower than for a LA (lead acid) battery. Generally, any Battery Tender or other motorcycle-specific charger will work fine. But, if the battery is especially dead, then some chargers will supply more voltage than is good for a gel battery.
For example, a Battery Tender Junior has a max charging current of 0.75amps. That is okay for a gel battery.
A Battery Tender Plus will supply 1.25amps. If the battery is dead enough to cause the Tender to run at max output, it can damage a gel battery.
With the Optimate 4 Dual Program, if you put it in "BMW mode", it will disable the Turbo (22V) desulfation mode and only use the Pulse mode.
Personally, I've been a Battery Tender and then Battery Tender Plus user for many years. But, of the 4 I own, I think 3 of them have simply died. I just bought 2 of the Optimate 4 DPs and am using one on my GS and one on my Suzuki. I've only been using them for about a week so far, so I can't really say anything more about them other than that they seem to work just fine, and all the lights on them give me a lot more info about what's going on than the 2 LEDs on the BT Plus.