Well, after some lengthy research time in understanding the terms and concepts of battery buying. Ive got a good layperson understanding.
I was safe in simply purchasing from Sam's yes.
But, I now know how to compare batteries for purchasing.
Mistakes can be made.
And its not the best practice to take the sales persons strong suggestion.
Did you know the temperature of your area where you live can have an impact on the type of battery purchased! Heck I've been lied to at the auto parts store. Did you know there really isn't a maintenance free battery especially if you want to get the most out of that battery...you're going to need a charger but not just any charger.
BMW driver...?
Best to charge that puppy up on the weekends and before long trips.
Letting the car sit for a considerable amount of time...?
Put the battery on a trickel charger.
Short trips inevitable, but not the best for the older (3yr old) battery.
There's a reason for all the different sizes and choices, it means something. Especially with all the different electrical components housed in the modern car.
Makes me think of my old 75 Buick...well thats another story!