I veg on hps... I like it more than MH for temps and lumens, but I like to flower with both HPS and MH... the added spectrum IMO helps a lot during flower.
Half my veg area is hps the other half is t5.
Where ever i have room is where I put them. I control the plant via super cropping etc so I dont really worry about it.
They are only in there a short time.
However If I were keeping mother plants I would prolly put in mh.
Ive been vegging with my 400 watt hps and I like the way they are looking,haven't used my mh too much,but i like the extra lumens and the difference in heat with the hps,bag seed at 24 days