I finally made the move to a Roto Grip ball and bought a Grand Illusion.  I bought this ball as a replacement for my Black Widow Solid and I must say that over the first couple of weeks I have been very impressed.  Reading through all of the reviews and positive comments on this site about the Cell led me to purchase the Grand Illusion.  I have also purchased a used Cell but have not found the occasion to use it yet as I have not encountered enough oil.  

Thanks to those who take the time to post info and answer questions it is very helpful to those like me who are trying to improve their game and their bowling knowledge.

Mark

Not knowing for sure which two you meant I will answer this:

The reaction of the Grand Illusion as compared to the Black Widow, the Grand Illusion make an earlier more continuous and controlled move to the pocket.  This has been true both playing behind the ball up the boards as well as moving in and playing the inside.  The Grand Illusion continues to drive right through the pocket and I have not left quite as many nine pins with it as I do with my Black Widow.  Hope this is what you were wanting as I stated I have not had opportunity to throw the Cell yet.

Mark

Edited on 8/21/2008 4:14 PM

The Grand Illusion is a great ball...I have had mine for 2 weeks now bowled 3 sets with it on a pbax league, 2 on scorpion and 1 on cheetah and it is great....All my equipment is Roto and I can rarely use my Cell because I don't ever find enough Oil.  I would have normally used the Cell on the scorpion pattern but I decided to try to use the GI and it worked awesome.  I have shot 654, 671 and 725 on pbax leagues.  I only average 203 on this league so Im pretty impressed.