Just for fun: Kenko 3x TC (live view focusing only) on a 70-300L f/4 (900mm equiv.) on a 6D
Here is yours cropped and lightened (top) compared with a Powershot SX50 at nominal 1200mm (in fact 215mm real) bottom. I think the $350 camera has the edge!
I wouldn't be happy with either of those shots, as they are presented here.
The "Kenco" one looks as if it has been ruined by being lightened much more than nessasery to equal the SX50 shot, on my monitor at any rate.
If it was me and I wanted a comparison I would start with an exposure I was happy with, and that would mean exposed to the right in this case, from both cameras. Then I would go to a "magnification" that produced a reasonable image.
If I thought I could not get a better image than I could get out of a $350 camera I would be very happy.
Unfortunatly I see much better results with my more expensive kit. So unfortunatly I have to spend more than you. I envery you your satisfaction.