This definitely falls into my category since I am speed dominant tweener with a medium rev rate.  (19-22mph ball speed, 420 rev rate)

I generally tend to go with solid or hybrid covers compared to pure pearls with what I usually see.  The big reason I do this is that the pure pearls with higher speeds generally won't have enough time to pick up off the breakpoint on many of the medium and lighter conditions.   An exception in my case is the Critical Theory, which is one of the very few pearl balls I can use on medium to heavy patterns and match up extremely well to it. 

On heavy patterns, I go with short pins and asymmetric cores.  On these balls such as my Defiant and Critical Theory, I always go with a 2-3 inch pin.  I also look for low RG/high diff numbers because I want it to be more core than cover and have a high flare potential.  On heavy oil, I typically drill pin below for because I want the ball to read as early as possible and to be smooth going down the lane. 

On medium and lighter patterns, I will go with longer pins (4-5 inches), and drill pin above.   I generally go with many of the standard balls with symmetrical cores that are intended for their conditions.  In these cases, I will go with a higher RG/lower diff ball which tends to make it more cover heavy and better suited for these patterns.  The difference here is that I will usually go with a slightly stronger layout compared to what most people will use in order to accomodate higher speeds.  In this case will use pin above layouts to give a good combo of length and backend.  I avoid high skid/flip layouts and high skid/flip balls since those would blow through the breakpoint.

With that being said, surface can be your friend with higher speeds.  I have taken balls such as the Nano and Defiant down to 2000 in the past when needed for tournament shots.  I have also taken balls like my Rogue Cell hybrid down to 500 on reverse blocks when I needed to have it react sooner.  Don't be afraid to take a pad and add surface when you need it.

For top weight, usually 2-3 oz, and will drill an x-hole whenever needed to add/reduce flare.

This should give you a good starting point.  If you have any questions about specific balls that you may be looking at, let me know.

TB74,
Thank you for that detailed response.  A lot to digest, and I may send up some names to get an idea. I may be doing my first full season league this fall, and the place is generally light, even when fresh. At least to my experience so far and from people I spoke to who have bowled there extensively. I was thinking a pearl but with low RG and high diff. But now I may concentrate more on hybrids, which kind of has me back to the drawing board. That's why I'm not listing some balls with this reply.

My thing is I'm not a slave to speed.  That is, more often than not I find myself backing off on speed to play the conditions with what I have. I can find grooves where I'm dialed in, but when I miss or lose it, it's hard to find again. So it would be great to find a ball where I would not have to do as much conscious physical adjustments.

I'm also going to the storm/roto demo day that lil league coach has been posting here. Any thoughts on which balls I should maybe focus on at that demo? I'm sure the hour goes fast, so I'm trying to focus.