I think Charlest misread your post because you have rogue cell listed, but he addressed it as though you had a cell pearl.  I would say that the nomad solid would be a decent choice in-between the rogue and the mars.  The riot polished, a cell pearl, or a nomad pearl would work well too.

I figure that the pearlized stuff will give you the best fit inbetween as far as overall hook, but the look at the breakpoint will be more angular than either of the pieces in your bag (as the Mars is kinda rolly for a polished piece).  I would go with the riot (polished) or the nomad solid if your trying to keep a similar look at the breakpoint with a somewhat inbetween reaction (though these will probably be a touch closer to the rogue than the mars)
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four fried chickens and a coke[/size=4]

Let me say something, let me say something...
AAAAAAAAAAAAAHHHHHHHHHHHHHHHHH

Sorry, I had not come back to this thread since I had replied.

No, Balls Deep, I think the Nomad solid is too close to the Rogue Cell. The NS is not a weak ball. The NS might be a goto ball, in the same league or tournament, for when the Rogue Cell is pinging 10 pins or burning up.

To fit between the RC and the Mars, the Nomad Pearl or a polished Riot is a better fit, as an arsenal. Actually the space between a Rogue Cell and Mars is fairly large.

That said, if you could afford it, I think you'd need two ball to fit between the RC and the Mars, the two Nomads or a Nomad Solid and a polished Riot should also make a better arsenal filler. So you'd have either
RC, NS, NP and Mars
or
RC, NS, NP and Mars.
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"None are so blind as those who will not see."