Just read this:
"If you connect a generator to a all-in-one or inverter charger, it can destroy it! It is not designed to work with the dirt ac output generator by most generators."
Does this mean I'm risking ruining my solar gen by charging with my cheap gas gen?
My experience with this: When solar was insufficient to get the job done (Maine winters), I recharged my batteries all last winter/spring using a Harbor Freight Predator inverter type generator, connected to the generator (shore power) connection of my Victron MultiPlus. Worked like a charm. We ran an AC line to the building that has the Victron in it over the summer, just to avoid pulling out the generator (for convenience only), but I'd use that little inverter generator again without a worry if I hadn't run that AC line.
On the other hand... We also have a cheap Champion gasoline-fueled generator (not inverter type) that we use primarily for remote tool power on the property (e.g., running large drills and drivers when working with 8" hemlock beams, nowhere near AC power). I use Stabil in the gas (works great, btw) but late each autumn I run the generator to get rid of last year's leftover gas. Yesterday, I decided that I didn't want to just waste that gasoline as I burned it up, so I hooked the cheapo generator to the to Victron to recharge my batteries. It worked fine to recharge, but the AC power it produced wreaked havoc with lighting in the buildings, which have Lutron Caseta switches. A small amount of strobing at all times, and when it started to get near an empty tank, it was like someone was turning the lights up and down quickly. I thi k this must be because the Victron basically "passes through" shore power.
So... Would I use an inverter-type generator? Yes, without much worry.
Would I use a non-inverter-type, cheapo generator? Maybe to recharge the batteries, as the Victron seemed to "clean things up" for that purpose (batteries recharged just fine). But I wasn't thrilled with the quality of power being passed through, so I'd likely avoid that in the future.
BTW, we also have a Kohler whole house generator (propane-fueled that is our primary backup power for the property) that is not technically an inverter-type, but the power it produces is so "clean" we basically can't tell we're not on utility power when it's in use. All the Lutron switches and electronics work just fine, and have for years.
Anyway, that's my experience with the situation.