Yea I think 6-7 balls per line is pushing it.

Personally, from working in a Pro Shop and bowling competitively I think about 4 per line would be good.

Something like:

1 Solid Reactive
1 Pearl Reactive
1 Particle
1 Particle Pearl

And...I think no more than 2 different cores per line.

I think by doing something like this you can allow bowlers to make better decisions when it comes to buying a new ball. If they want something longer all the need to do is buy whatever in that line would be below what they have.

Like what Brunswick has in the BVP line. All the same core (I know the rg is a little higher on the Goliath) but they have it all covered.

IIRC, the original Inferno was released in January or February of 2003, so it was in the catalog for 2 1/2 years.  I had heard that the Inferno was discontinued because its sales were ramping down.

The Zone Classic came out last Summer, so I'd envision that it would remain in the catalog until next Summer at the least.
--------------------
...formerly "The Curse of Dusty," and "Poöter Boöf" before that...