The whole gel battery is misleading.
The YTX and YTZ model batteries or at least the GS, Yuasa, Varta and other main brands ones are AGM. Not your standard lead acid sloshing around jobbies.
AGM stands for Absorbed Glass Matt.
Basically you fill the battery with the acid pack (YTZ are seal in factory) allow to stand for 24+ hours and the glass matt swells and absorb the acid forming a gel core - which is all the "gel" batteries are.
This gel heats up, can't "bubble away nicely" like a liquid acid battery - when you use a car charger the 'gel' overheats and swells the whole battery possibly to the point of fracture. Acid in your eyes and over your bike isn't good and I've seen it on owner charged bikes in the workshop the the owner claims have been on charge all winter and come March fail to start - yeah all the acid in on the floor and trashed the bike on the way down.
These gel or AGM batteries are designed to be tilted or turned on the end/side and function normally.
An old fashioned unsealed battery would spill or vent the liquid acid out or at the very least the acid will not cover the whole plates and cause a lower than desired output.
I've got a motobatt on her bike as it was the cheapest branded battery I could get locally (M&P's is 10 mins away) and it's been fine the last 4 years.
The Yuasa on my Varadero is showing signs of age and is only 3 years old. Not holding a high charge and will be replaced with a Motobatt as the Yuasa has been discontinued and the alternate fitment is £140
Lets also say that even Yuasa don't make them like they used to and only offer a 1 year warranty and that's only if dealer filled.
The 1400cc engine turns over just fine, but I've used jump leaded from the good motobatt on the GSX (engine not running) and it struggles to turn over the Varadero.
It's and about volumetric compression. A V-Twin will require a healthier, stronger battery to turn it over than an inline 4 of equivalent or even greater size.
So if your v-strom battery is starting to go, it'll fail to start the bike quite soon.