I have 5 Tender Juniors, 3 that stay plugged in outside in my cold shed on my motorcycles, all batteries in those are OEM and all my Tenders have been great, one of those bikes is 10 this year!
I use them on my Ballistic 8 cell (1 year old only) but don't leave that one unattended, also have the ballistic charger, and an older 'super industrial' charger for non-trickle situations.
So far the Tenders and my 2 ballistics have treated me well, I have had skis for 25 years and rarely does any ski battery last more than 2 years for me.