@ wajo, Joe, rkg : thanks for your interest/input.
I tried what wajo suggested, ran the coax through the Maggy while power cord still unpluggeg and checked the signal in the TV tuner, then I re-plugged the Maggy. Well, the signal actually went DOWN after the Mag was plugged back in
Take WCAX's example, with Mag unplugged I had about 67% and after I plugged it, 62.
On WPTZ, 87 vs 82.
On the Mag (so, obviously powered on) I get WCAX @ 18 and WPTZ @ 23.
Just to compare, CBFT (local public station) comes is at 92% in TV, 86-90 in Mag. So, technically, on local stations, the reception is very similar (max 5-10% difference - not even close to the huge discrepancy on the US stations)
Altough, for 3 stations (CKMI, CFJP and CFTU), the difference can reach 20% less on the Mag. Still, very far from going from 87% to 23 on WPTZ...
I was also very surprised to realize, after almost 24 hours of remaining unplugged, the Mag still had the channels in memory after I plugged it back in. How in the World am I suppose to reset the Mag? I did leave the coax cable plugged, though (apart from when I did the above-mentioned test). Didn't think it'd make a difference, anyway?
rkg : I've been thinking the same. Local stations are coming in very strong, so perhaps there's so saturation going on. I tried the hanging by a thread trick and such, never made a difference on the results.
Note to self: I should try setting the FM trap to "IN" on my CM7778.
As far as changing the orientation of the antenna, not possible. It took me HOURS of fine tuning to find the perfect spot (with me on the roof, on the cell phone with my wife indoors who was watching the signal meter on the TV). Those US stations are so fringe that, even a 1 or 2 degree change makes a World of difference. I can go from 80% to 60% by moving it a ¼ of an inch. On the other hand, the local stations are so close that this allows to not aim them directly (by aiming the US stations, I'm not aiming at the locals).
I don't know anyone who has the same type of OTA setup in my area. Would be hard to test the Maggys elsewhere in similar conditions.