Re: What's the brightest and punchiest sounding speaker?
brightest and punchiest that I'VE TRIED and OWNED and not just read about or heard in a clip would have to be whatever Genz-Benz puts in their G-Flex cabs. The metal grill doesn't hurt the brightness either, but those are some high performance speakers, whatever they are.
Next bright and punchy, that I've actually tried and owned, would be a '93 Bogner 412 with V30s (one of the very first Bogner cabs. 1st, 2nd, or 3rd one, not sure).
Next, again, that I've actually owned, would be a Marshall 410 with Fane speakers.
My current cab is the darkest I've owned (Bogner puts a water heater blanket in his cabs), just to contrast the above and add to (actually, subtract from) your X-pattern idea. It is a Bogner Uberkab with V30s and 75s in an X. Punchy, balanced, but not "bright".
I think you can get brighter and punchier than this: "I was thinking of maybe an X pattern V30/G12H 4x12?" Because to me the X-Pattern thing is about a more balanced sound with more frequencies coming out.
I'm interested in a 112 cube with a 100 watt Sugarcone in it....