Well - I grabbed up a lince2 for my son so here's my review
First thing - with my cressi matrix it often takes a bit to get it settled right on my face - it will leak slightly if, for example, you open your mouth extra wide to get that last grab of air before a dive - unless it's settled on just right. No biggy since that is an action one can do without - but it is generally sensitive to face movement. If anything it tends not to leak under pressure however. I dove awhile with it today and it is really not a problem and, like I've said - I like the 'wide-open' feeling of it's fantastic visual field.
The lince is like a scaled down version of the Matrix - it has a very narrow skirt and the silicone is proportionally thicker and less flexible. It does not fit my face very well and tends to leak at the temples. Peripheral vision is less than the Matrix by quite a bit - probably 30 degrees or so total - this is really the strong point of the matrix - particularly for spearfishing - the overall visual radius is just outstanding.
The fairest comparison for the Lince2 is the Omer Alien:
Vision: Pretty much a tie - with the lince having an insignificant advantage downward and being pretty much identical in the perphery. Upward I'd have to give to the Alien - at least in the center.
Fit: No contest - Alien has a wider, softer skirt. If you are looking at these masks get the Alien - it gloms onto your face and stays there, has a very good visual field and is more compressible than the lince2.
I think marketing the lince2 as a freediving mask is just that - marketing. It's really more like a version of the matrix for smaller faces.
I've never tried a mask as comfortable and good sealing as the Alien.