Both approaches obviously work... I'd argue that the extra range from a mast mount is not a significant advantage at the speeds and the conditions that we use our radar - I've never had it on max range anyhow.
Ours is on a stern post, it's integrated into the stern railing so certainly doesn't clutter the cockpit - but my primary reason was to be able to mount the display unit at the helm, where it makes more sense to me, than below.
With a small unit like ours the post will likely weigh more than the radome, but we've had no issues with our 2" SS post fabricated by a welder/machinist friend.
We have friends with a Passport 40 currently cruising in Mexico, and a larger radome on a gimballed mast mount. For reasons not exactly clear last month the welds on the support tubes failed and the radar was barely hanging on and significantly askew. Whether this was due to the drag of the tacking headsail, or simply the motion and mileage of long distance cruising we're not sure.
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)
1984 Fast/Nicholson 345 "FastForward"