With much advice from you guys on WP, a couple of months ago I made the jump to a 7D and a Nauticam NA-7D.
Nauticam's distributor in the UK, Underwater Visions / Dr Alex Tattersall (Alsky on Wetpixel), worked closely with me throughout and the system has evolved into exactly what I wanted. Between us we 'discovered' a few things along the way too, like using the C60-MR130 macro port (and extension) with the Canon 100mm L IS. Using this port allows me to also use INON UCL-165 and UCL-300 diopters (M67 threads) which really increases the flexibility of the Canon lens.
Underwater Visions has my unreserved endorsement and recommendation as a supplier of the highest integrity and service. Thanks very much Alex.