I do not own 12L but own both Quad 11L & Compact 7ES. While the 11L may be revealing however I think it is not as revealing as the C7ES, and C7ES is obviously in another league.
C7ES is much more superior in term of highs, imaging and overall smoothness, and sound effortless with most kind of music. When I compare Quad 11L to other of my moving-coil speakers collection such as KEF LS3/5A, Dynaudio 1.3MK2, Proac Response 1SC and C7ES, I am pretty sure that the midrange of 11L is somehow over-emphasized. To put in another words, somehow the midrange is designed to sound overly loud/or rather over forward in contrast to background music. Listen to some Choral works/Vocal and you understand what i meant. But this can be compensated by choosing different cables/Interconnect or switch you pre-amp. I drive them with my tube gears.
However, I do not think C7ES sound warmer that the 11L. 11L is one of the warmest sounding speakers I have come across.
But it is the overall tonal balance of 11L which attracts me. It is non-fatiguing with good musicality and natural sounding. Just the opposite to the Dynaudio 1.3MK2. I found myself hook on to it after hrs of listening. I start to appreciate the laid-back highs from the Quads, they sound very different/special to me, which i do not find these in C7ES, Dynaudio and Proac. I think these is one reason makes the Quad far more non-fatiguing tha the others.
If you have extra budget, i think you wont make mistake by getting a pair of QUADs. They are real good at their price. No other made can rival them at the price range.
But IMHO, the C7ES is much superior because they image much better and more neutral sounding, couple with their natural mids and conherency.