Lighting question in grow tent

hi all and thanks in advance for the advice i currently run 2 secret jardin dr120 one for veg and one for flowering i have a 400w mh in one tent and a 600w hps in the other i grow in soil 5 gallon buckets 4/6 plants at a time i have been thinking about upgrading the 600w to a 1000w and using the 600w for veg my question is would the 600w be overkill for veg and would yield still increase with just 4/6 plants or should i add another 600w to flower tent and keep the 400w for veg or what do you guys think would be best thanks in advance

 

thanks for the help in my 600w tent the temp under the light at plant top is 78 degrees how much of a increase in the temp will the 1000w make and one last question should i be measuring the temp right under the light thanks in advance again

 

thanks for the help and smartlamps i run 2 tents one secret jardin dr120II and a cheap 4x4x6.5 from amazon that was like 99 bucks i use for veg they both work great save yourself the money and get the cheaper one the only difference is that the secret jardin has a ton of vent ports and cord ports and the cheap one only has 2 ports but as far as light leak they are both the same they both leak a little about the same if i had to do it again i would have saved the money and bought 2 cheap tents unless u really need like 8 ports