I haven't used one, but I did look at them.
I have a disconnect switch on all my batteries, first thing I do when I park it for storage is disconnect tyem. Try to have them as fully charged as I can.
I'm in the South so not dealing with low winter temperatures really, but I've gone up to maybe around 3 months or so with no problem.
I have a smalle battery minder about like this one
022-0150-DL-WH
on my boat battery that sits very long periods of time between uses. Has worked for a number of years now. Before getting this, I replaced way too many batteries in boats and pupoups.
That same company makes solar trickle chargers.
My take...... if you are going longer than say a couple months in storage and can't do a plug in trickle charger, I wouldn't hesitate to do one of these little solar ones.
Even when disconnected, these batteries will loose roughly 10% per month....so assuming you start with 100% you've only got maybe 4-5 months. Now start less than full, and don't disconnect all the parasitic loads, then you're asking for a damaged battery. Solar can't hurt!