I agree 100% with you, but there's no financial advantage.
The deluxe system.
Let's say you buy 16 batteries @ 100 bux/each, the total cost is $1,600 US.
As the batteries last twice as long, let's say 6 years, it costs you $1,600 US for 6 years.
Cheapo system.
You buy 8 batteries @ 100 bux/each, the total cost is $800 US.
As the batteries only last 3 years, because of the greater abuse, it costs you $800 US for 3 years, or $1,600 US for 6 years, same price as the deluxe system.
The only advantage would be in the 16 battery system being able to endure longer power failures.
I guess it all depends upon whether or not you have to pay for;
1] Battery delivery.
2] Battery installation.
3] Battery maintenance.
4] Removal of old batteries.
Not to mention the "down time" associated with the installation of new batteries.