I agree with you that DKJr with better graphics (and platforming physics closer to the arcade version) would make a wonderful addition to Opcode Games' library. In fact, I even did some graphic work to that end roughly two years ago, while I was working on the graphics for Donkey Kong Deluxe. It was sort of a graphic R&D side-project.
Eduardo can do it, he can do anything!
Donkey Kong 3 is possibly one of the worst games ever made and I wouldn't ask anybody to waste their time porting it to any system. Donkey Kong Jr. is on the other had a stellar game and if you're gonna bother with Donkey Kong you might as well do Jr. as well.
However, even if Eduardo wanted to do DKJr (which I'm pretty sure he doesn't - Do correct me if I'm wrong, Eduardo), the game wouldn't fit into our release plans very well. You see, the release of Donkey Kong Arcade implies the release of the Memory Pack (the 16K RAM cart that goes into the CV's expansion slot) because the original DK arcade game requires more than 1K of RAM. Once the Memory Pack is a reality, Eduardo will be in a good position to release a string of titles, namely Goonies, King's Valley, Yie Ar Kung-Fu 2, Knightmare and Zanac. All of these games are already ported and working on the CV (I tried them all during my visit to Eduardo's place last year, so I can personally confirm this) and each game only has a few minor issues to resolve before they are ready to be put on cartridges. A lot of effort will have to be put into producing the boxes and manuals for all those games, so really, where does DKJr fit into all this?
Of course, all of the above is based on the premise that Eduardo will eventually get around to finishing Donkey Kong Arcade in the forseeable future, and that hasn't been confirmed just yet.
I've played the SG-1000 game with Meka, and it's a fine game worthy of a CV port, but I find there's a problem: Jumping around platforms is frustrating because more often than not, you end up bumping your head on a ceiling when you try to jump up to a higher platform, falling down, and then falling prey to a roaming cat soon after. And that's with a PC joypad, imagine the aggravation of using a standard ColecoVision controller with such a game! I have hand cramps just thinking about it!
In all honesty if I had my choice of any one game port for the ColecoVision it would be Sega's Flicky. I never played the game in an arcade as a kid, in fact I never even remember seeing one. I found the game through Mame some years back and I love it. I've got it for the Genesis, and I also know it was released for the SG-1000. And since the Telegames Personal Arcade can play CV and SG-1000 games I would think that it would be able to be ported somewhat easily. I can honestly say that I haven't played the SG-1000 version so as far as I know it sucks compared to the original arcade or Genesis port, but the game is fun as hell.