Jack, I can only speak from experience wrt using a TT sat nag on the K13GT. but I would guess that, regardless of sat nag make, you would have a partial obscurity issue, albeit a minor one, as I referred to in my previous post. I've found that with adjusting the two RAM balls (on the mount and the sat nag plate), you can improve speedo visibility, but it's a trade off between a partial obscurity and a cockeyed facing sat nag! The Garmin boxes, being a much squarer shaped unit, could obscure more...?? Just a thought.....
Despite this (minor) partial obscuring, I do find this sat nag mount location a good one. No vibration and a nice tidy routing possible for the sat nag cable to under the battery access panel.