I've seen some confusion about the Waterloo neck options so I sent Collings an email for specs on their two main profiles. I received this diagram and found it helpful so I figured I'd share it here for others deciding between the "Pronounced V" and "Oval" profiles.
I tried out the WL-12 all mahogany model with the oval neck and I loved the feel. I'm a fan of full C / oval shaped necks in general. It felt just right for me, not too thin or too chunky.
The thing that does stand out to me is how thick the oval neck gets at the 9th fret... I'm wondering if this is due to the start of the heel on the 12th fret model? If anyone can verify these numbers on their own waterloo I'd be curious to know.
Hope someone finds this helpful!