I have not tried these strings on my 814ce, but I love them on my all mahogany Guild D20. They are very warm (not bright in the slightest) and last a LONG time for uncoated strings. Where I may normally get around 25 hours of actual playing time from most uncoated strings, I've had the Martin Retro Monels on my Guild for over six months now and they're still going strong.
If you want a significantly less bright guitar tone from your 12-string, I think you'll be happy once you try these strings. If you want the typically bright Taylor sound, look into other strings.