Hmm, good stuff. Here are my rules for forming different minor chords (courtesy of Danati), using C as an example:
Cm= C major with a b3
Cm7= C bass with a major chord built off of the b3. So C/ Eb G Bb (Eb major)
Cm9= C bass over Eb maj 7= C/ Eb G Bb D
Cm11= C bass over a major chord built off of the b7= C/ Bb major=
C G/ Bb D F.
It may seem confusing but when you get the hang of this, any minro extension in ANY key is possible for you.
Fenix, we voice our 11s the same. I would just call this a C11 chord though. The "m" symbol denotes minor, which relates only to the the 3rd degree. This chord has none, so it cant be called minor. Now in practical situations, it would only be used in minor or dominant situations, because it cant work with a major third. So I can understand why you call this a minor 11. Lets say it did include a major third, the sound would suck because of the 11th and the 3rd being either next to each other or a minor 9th away (which is usu. to be avoided) is a nono (there are exceptions) but not with the 3rd and 4th/11th degree.
The only way to have an 11th in a chord that includes a major third is to augment the 11th.
ie a C9#11
C E F# Bb
For an audio example of that exact voicing of the C11, listen to Street Life by the Crusaders or Red Clay by Freddie Hubbard
Oh yeah, I dont know if you noticed it when you did it Fenix, but another way to figure out your 11th chords on the spot is to play a minor7th chord off the 5th degree of the chord.
I tend to think of it a lil different though. I play a major chord a whole step below and turn it into a minor7th, by adding the corresponding note with my thumb. In this case a G.
C - 5th degree is G
therefore G Bb D F is a Gminor7
So you have C/Gminor7 (you might even see people call it this way, sometimes not knowing that it does indeed have a name)
or C/G Bb D F