I am running 888s and the grip is second to none,but I only use in the dry and for trackdays and sprints.
Put 245/40/18 on all four wheels,but yes it will alter gearing a little but the speedo will read the same
as its driven off the front near side wheel which will have the same aspect ratio as the standard tyre.
Wear rate is subjective to what your doing but 2 or 3 all day trackdays would muller the fronts!!
Previous to the 888s I ran the Ad08s and although the grip is way down on the toyo's IMO they are the
best all round tyre if you do have to use your car as a daily driver with a few trackdays mixed in.