your 8 channel digital inputs are at the moment not used....
now, you want a mixer for that 'real handling feel'.....because you don't seem to be too concerned about recording "real" instruments and sound like your mixing in the box...maybe a hardware controller would be more up your street??....so basically you can control the mixer in logic via 'real knobs'
now - there are issues with this - ive yet to see/hear a pure control box that's 'exactly' like a mixer.....and they are quite expensive....
....you also want to be able to 'flavour' the recorded tracks with an analogue mixer.....and, in the future, record some "actual" instruments into logic (or even some mic'ed instruments??)
and you want to keep your converter....it's something your used too....and you feel like the input side is redundant, and that cost you money as well, so you'd like to use it.....
ohhh- and no budget ball-park figure.....which makes things a little tricky....
ok.....there are options.....however, I am not sure you'll find a reasonable, cost effective 8 channel mixer with digital light pipe converters (because the mixer will have to convert the analogue signal to digital for the mytek)...much better to use those inputs to run, lets say a behringer ada8000 - 8 mic channels with digital conversion - into these as 'optional extra' input...there are other, more expensive options - but a lot of people rate the ada8000...even if they dont rate any other bheringer gear....
The most ideal product for you would seem to be either the allen and heath zedr16, makie onyx 1640i or for double the money (but nice..and a better spec'd daw controller) SSL Nucleus
Now - all the above have been reviewed (favourably i might add) in SOS....the A&H and Mackie are like traditional mixers, with a firewire connection to record into your daw. The Allen and heath has a very neat way of returning your signals from logic on a track by track basis, mixing with the eq etc (all with the touchability of a desk) and returning/recording that mixed signal to the DAW...i think the mackie does the same......the nucleus is more of a control surface kinda job with additional in out channels...but what nice channels...and a superior control surface spec (motorised faders etc) than the other 2....and includes duende plugins ....but doesnt have the dedicated knobs per channel of the other 2
your mytek inputs are still somewhat redundant...but you can still monitor from your mytek outputs..using the desks as input/mixing 'module's' and hearing the results from the mytek
the digital to analogue converters of all the above are pretty good tho.....you 'could' sell your mytek to fund/part fund your purchase??
or just buy a box o knobs/sliders (behringer again - novation make some as do others) and control the mixer in logic with 'real' knobs and sliders
you should take a look at the above and see which ones fit more into your workflow --and have a budget of somesort -
and the Elf will (using some very convincing and relevant arguments) try to disuade you from buying any kinda mixer and get used to mixing in the box - it is cheaper and £ for £ your plugins (UAD/SSL etc) are cheaper and more effective than buying a mixer....especially a sub £2000 one.....but im more on your side and would love a ZedR16!!