Don't mean to be bolshy but why force MAP mode down throats. HSI mode must be there for some reason because it has its own glide slope too..
I think the key phrase is 'situational awareness': HSI give you some SA, MAP gives you a lot more. I advocate ND with EGPWS, PFD with WX RADAR, TCAS and Lightning Sensor on both. After a while, looking at the HSI makes you feel blind!
It's a helicopter, but I think you'll agree the principle is the same:
