Of course you can, but is it worth the extra expense?
98% - 99% of our customers use their DIY BrickWood Oven for about 3 - 5 hours at a time. If you plan on using your oven 3 - 5 DAYS at a time, we would recommend ceramic fiber board.
While it true that CFB helps retain more heat than the Perlite or Vermiculite insulation blend, most of that heat retention is measured in hours, not necessarily temperature.
The other important factor you need to look at is cost. CFB comes in pre-cut shapes / sizes and most of our oven bases require 2 sheets of standard size 2" CFB. When the average cost of CFB is $100 per sheet, right there you are at $200 for insulation. THEN you have to factor in the cost of shipping via truck freight since UPS and FedEx will no longer ship CFB. So now we are at $300 - $350 just for the insulation board (vs. $50 for Vermiculite / Perlite insulation).
Another way to describe the difference is the BBQ analogy… You can spend $3000K on a top of the line 48" gas grill with 8 brass burners that pump out a mind-blowing 100,000 BTU’s for 3 days before refueling… or you can buy a $400 grill that cooks your hamburgers just as fast and thoroughly as that Ferrari BBQ.
If you’re going to cook for lots of people for several days, you should get the $3K grill… If you just want to cook for your friends and family every-so-often, the $400 grill is more than fine.