Ohai there, I'm back and randomly awake at 6 in the morning where I should be asleep.
To reply to your first statement, the answer is yes and no.
Metagame development-wise, I would say Sonic has made hops that DK could only hope to make. Sure there's some ATs found for him and all that stuff, but Sonic has improved more since the game (!) was released.
Face value stats, no. Donkey Bong has a good balanced of speed, power, and range. Sonic only has major Speed, average kill power, and his range compared to Donkey Bong is rather lackluster. If you want to include the recovery category Sonic has him outclassed there but then again most everybody else in the cast is outshined there, even in the game of Brawl. Donkey Bong also has some matchups he is better in, overall a better character... when you don't factor King Dedede into the equation. You could argue that Sonic isn't too behind, if not further ahead just because he doesn't have a "get-*****" matchup to worry about, and comparing these two to each other and the rest of the cast... soloing Sonic ain't no walk in the park for sure, but if you want to do it you could (I know I am).
I only hope I answered that rather well, this is just my observation.
Oh, and if you're at all curious about my tourney performance, I got 5th out of 11 entrants in singles, lost to the people that ended up placing 1st and 2nd respectively.