Sir i think u do not have aesthetic sense....mixing can be done but it looks very weired. Also u must be aware that humsafar is a separate concept with coaches with beautiful curtains inside, CCTv in coaches, Antodaya is a separate concept with RO in coaches, Duronto is a separate concept with coaches have heaters for food. But in some of the Red color LHB coaches do not have heaters for food. So mixing all together is not good along with from aesthetic look.
All 4 types r different concepts introduced by IR at different time periods based on different requirements r situations .