The Emerald will be a little longer than the Cherry.  The Cherry is really suited for medium shots, not light oil, as it has a very strong, and earlier, backend movement to it.  The Emerald gets a little more length than the Cherry, but with the Max-Flip reactive cover, it gives you a hard angular snap off the dry.  In my opinion, stay away from the Cherry and go with the Emerald.  This ball will cover more of the lighter oil conditions, while still giving you the versatility to be able to play on medium oil house shots.  

Also, if you are looking for a true dry lane / 10-pin ball, you should look at the Razyr.  This ball is strictly made for light oil and spares, and would be a great addition to your arsenal.  It is a high rg, low diff. ball that will roll very smooth and consistent on lighter oil patterns and spares.  

I think if you went with an Emerald Vibe and a Razyr, along with the equipment you already have (Crime and Widow), you should have most shots from medium-heavy to light oil covered.
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MainePBA
"I'd rather be a conservative nut job than a liberal with no nuts and no job."

I just Drilld and Emerald Vibe, Up-Rising and a NVD and on a house shot the Emerald Vibe is by far the strongest. The NVD burns up way to quick and I knew it was going to while drilling the ball. The Up Rising is drilled the same as the Vibe, both balls have a 5 1/2" pin to pap distance, but the Vibe is alot stronger off of the spot which makes it cover more boards.  Now how the Crime sounds, core and coverstock wise, its might be close to the Vibe so I would either drill the Vibe with a 6" - 6 1/2" pin to pap or try out the Rayzr. Good Luck!
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Ebonite - "Bowl to Win!"

link for some pics of my arsenal:
http://s201.photobucket.com/albums/aa41/bowl-2-win/Fall%20Arsenal/

thanks for all the comments. although the rayzr sounded good, a friend of mine that tried it said it wouldn't be any different then my Columbia u2 urethane that i use for spares. just trying to carry less balls. i think i might go with a emerald vibe. would it be better if i added more polish?

Your friend is comparing apples to oranges.  
Early 1990's  2-piece urethane versus a modern reactive 3-piece core?  

Similar amounts of flare maybe, but the coverstock is going to be the major difference here.  

If you have the Black U2 it is probably just smooth reacting from the heads to the pins, if you have the Pearl U2 I could see it being a little more similar to the angular reaction of the Razyr.  Maybe...

The Emerald Vibe is already very polished from the factory.  If you wanted more length, you could try Powerhouse Extender Polish.
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"A word to the wise ain't necessary -- it's the stupid ones that need the advice."  Bill Cosby
"Never argue with an idiot. They bring you down to their level and beat you with experience."