High Alumina Firebrick

Hi guys. I'm busy planning an Alan Scott 32x38 oven and having a big hurdle on Firebrick availability. I live in a country that imports Firebricks and only high duty - 38% and above. If this is all I can get hold of, how will it affect bread baking? At this stage I'm considering the high duty bricks for the hearth and clay bricks for the dome, but if I just end up with overcooked crusts then this might not the the route for me.... If this oven is built it will probably be used two to three times per week for bread and regularly for other general home needs. 

Alan Scott recommends only low to medium duty, but the following excerpt from traditionaloven.com implies that it's not such a big deal: 

Apart higher co$t, additionally, higher Alumina content grades make these bricks harder and brittle (more glossy if you like) making them absorb less steam e.g. from under pizza dough bases being cooked or bread dough. However one can get used to cooking in such oven fast.

Even though you can hear other words from a few suppliers who sell not locally manufactured product, conductivity and heat absorbing capacity is not influenced much at all by higher or lower alumina content. Higher grades won’t create magic temperature difference in cooking environment and vise verse. Main reasons for this are modern imports, one high alumina range suits all business and applications, less varieties to stock, higher markup and margin, those are the reasons if 18% to 26% brick isn’t sold by a store. 

Thanks in advance :)

Matt.