Thanks to both.

As (bad) luck would have it, I remeasured the hole the center must fit and the VP180 is faaaar too wide to fit in this space anyway.

The VP150 is the biggest model that I can actually fit in the space. Certainly not the end of the world, but would really have liked to have at least had the option of the VP180, particularly if I decided to go with the M100's over the M80's.

C'est la vie!