I threw the Mercury for a month or so in the fall season after it came out that summer. While the Sonic X was a drier lane ball, it had a rolly look to it, much like a polished Low R.G. ball yet it never overreacted to the dry. The Mercury was great on a fresh house shot for playing the friction(It's stronger than a Sonic X), but was a bit more sensitive in oil, even on transitioning drier patterns. This made the Mercury seem like it would recover from shots missed into the friction and skid forever on shots pulled into the oil line. I tried it with some surface on it for a week or so but the cover never really wanted to read in oil. If you want a more angular reaction on drier patterns and have something else you can switch to when the Mercury gets a bit over/under then I'd drill a mercury.
When we were drilling them up in the shop, we gave alot of guys a 2" pin to PAP layout just to smoothen out the ball in drier conditions. Alot of people loved it that way because in drier patterns they still had alot of control.
--------------------
-DJ Marshall
...The Twelve In a Row Pro Shop