Ace, I haven't had any trouble with my Champions (2 years old, also from Sam's) but I wouldnt be afraid of the Energizer brand...I think that most batteries come down the same line anyway and just the ID is different......
Just to add to what Len says below, I made a copy of my battery reciepts and put them in my log book. All batteries on my bus came from Sam's. (2 grp 31's, 8 Golf Cart batts, gen start batt and also the batt in my VW toad) Without the receipt, the warranty goes from the date code instead of when it was purchaced, as most know already...... FWIW