What is the cost comparison of brake maintenance when using only idle REV, as is often demanded by many airports, and the cost of brakes using NO REV? This would then bring in the question of what is the cost of installing TR's in the first place. As they are not considered in normal RTOW calculations, nor landing, one wonders are they worth it? There has been smaller jets, Bae146, that didn't have any. People will know of more.