This is a avideo of Super Meat Boy i have made using Movie Maker, it's a montage of some of my early moments in the game (up until rapture..). I have put some effort on it so.. give it a chance.

http://www.youtube.com/watch?v=5IzIyf6dZaI&feature=channel_video_title

Try to finish levels with a limited amount of jumps
Try to beat the dark world with crab
Try to clear all disappearing tiles in all the levels
Try to collect all bandages without dying (you have only one shot at this..)
Try to get A+ in all cotton alley dark world levels without dying ("Impossible+ Boy")
Try to beat all levels with no more than 20 deaths (you can also vary that number..)
Try to beat The Kid without dying

KEYBOARD!!
I use keyboard, i use the "down" arrow for sprinting and "space" to jump and I find it very comfortable. I can tell you that my fingers don't get too much strain, but it also depends on the keyboard. I have a Toshiba laptop and the buttons are very "easy" to press compared to some old keyboards that have very "tall" buttons

My suggestions:
1- Having a life limit on glitch levels makes no sense, because it's only one level. Make it endless, just like in normal maps.
2- Make the leaderboards useful. Add a level by level leaderboards and a chapter by chapter leaderboards. REMOVE THE CHEATED/BUGGED TIMES. Oh, and the scores should be only the sum of your times, not strange formulas to make the number big...
3- You can't replay the level if you saved your replay. You have to go back to map and choose the level again. This should be fixed.

I totally agree with the three lives limit in glitch levels! That's one of the few things in the game that are frustrating without making any sense.
Regarding the button configuration i would like to suggest using the "down" arrow to run (you can change it by yourself..). I found it to be really confortable

Is the joke Potato Boy or the decreased difficulty on harder levels?? (that would really suck).
Between i just tried the expert remix and i loved the ingenious difficulty of the levels (i love to see how a level can transform into harder versions of itself )
 

You will ruin all the fun of going through every level in the game. I find that one of the best things in SMB is the difficulty level that rises constantly through all 300 levels from the forest to cotton alley dark world

Not a speed run by any means, but just a replay of Hush, which is one of the few levels that drove me to frustration. 

http://www.youtube.com/watch?v=RSOOHI1jGZA

OMG!! Are u serious?? this was one of the easiest levels for me

yeah.. try the dark world version of omega

What's cool about SMB is that achievements are REALLY achievements, even completing the light world feels like a great achievement for me.
I don't think there should be an easy version of some achievements, since that would ruin their uniqueness. My suggestions:

"Bandage Boy": get all bandages( is there an achievements for bandages already?..)
"Perfect Boy": get A+ in all levels
"Insane Boy": complete all levels without dying(  [D8]maybe not...)
"Nice to meat you": press start game for the first time(just kidding )
...dunno guys, actually i think they should not add any achievements until we get the editor.
Then we may see achievements related to levels you published( like in LBP), even though i prefer that achievements refer just to gameplay.

how do you get the achievement? All levels and all warp zones + all bandages?

Come on guys, cotton alley is just out of question. I'm goin nuts just trying to beat it normally. Why would anyone one waste his precious lifetime trying to do it without dying ONCE, just to get a stupid achievement that none will ever see or care about... Im sorry this is just the result of being frustrated by the game
Ok, good luck practicing and practicing, but for me a no death achievement in the forest light world is enough . 

I'm very proud to say that i beat the forest light world!!
I don't know if i want to try others, at least not before i can get the Kid