Joe Black :
I still feel that they should split the headset from the computational device. The headset should be as comfortable as possible.
I definitely agree. This is the approach taken by Magic Leap, although it was more of a necessity for them.
Here's a thought - if the HMD supported some sort of wireless connectivity standard, then you could use the same HMD both with a PC and with a hip-pack or backpack compute unit. Maybe high-end cell phones would even pickup support for the wireless standard.
Anyway, the main downside would be more cost, if building two units + a connection cable. But the benefits would include more battery life, more comfort (obviously), and more horsepower (i.e. the compute unit could generate more heat and accommodate better cooling).