Nothing personal.

There's only one way to solve this dilemma . . . MythBusters style! We should come up with some tasks for a 65816 and a 68000 to solve, and time each of them. Maybe we can pit an emulated IIgs against an emulated Atari ST, and see how they compete.
Rather baffling that any hobbyists haven't done ...

As the thread starter, I don't think it's OT at all, and if you want to go off trail please by all means do, as long as it's a natural progression. There's nothing worse than someone who comes in and stops an interesting talk by pulling the OT card.
If you mean OT with regards to the forum, I don't ...

About 65816 being faster than 68000:

Listen to what Woz has to say in a 1984 byte interview:

BYTE: How is its performance compared to the 68000?

WOZNIAK: It should be available soon in an 8-MHz version that will beat the pants off a 68000 in most applications, and in graphics applications it ...

A 65816 would have meant rougly double the power of a 68000, with BC to all 6502 code at a lower price.

Actually, a 65816 represents about 0.8x the power of a 68000. What makes the 65816 appealing is the amount of performance you get for the cost . (The 68000 was much more expensive a chip.) But ...

Looking at the C128D layout I got inspired thinking up a revisionist "what if" situation.
What if Commodore had actually used the budget on some worthwhile hardware that could actually be used in conjunction, instead of being split up into each its own little domain?
Let's just list the real C128Ds ...

Ok, simple question which I haven't been able to find an answer for anywhere.
How many transistors is the 65c816? Or alternatively the die size.