Hey dude, never ran grand daddy purps or sc kush but I can possibly provide a little insight on the t5 scenario regarding 6-9 plants. In my opinion, for 6-9 plants to fill out a 1000 watt flowering space (5 x 5 max) you'd want to consider two things. The t5's will veg them just fine but 1) the structure of the plant will be nowhere near where it would be using a 400mh of one of those 250 something watt veg lights (so thats hindering all those nice tops that will be producing dank buds, ultimately affecting your yield) and 2) if you go t5's to save $$ you'll need at least 2 bare min 4x4 t5's. 9 is a nice number, 3 rows of three haha. And need to make sure when you flip them too a 1000watter you put the lights as high as it can go in the room for the first day or 2 then move it down slowly. Your going to shock the fuck out of them unless. Another thing, your veg time will be longer to get them to the size you want to fill the 1000w space. I'm not sure if the genetics your using are slow veggers or not. But keep that in mind too. I know I ran into a slow veg plants and it took a heck of a long time to get 4 to fill up the space. Like 3mths total from seed. Mind you I also used t5's for veggin them initially until I went out and got a 400 to veg em. Out of curiosity if you can play with your numbers ( since you suggested 6-9.) Easiest way to work around this problem is bump your numbers up, go
sea of green single cola style with little veg time. That way no worry about 400, still prevent against shock and focus on one top per plant. Only thing is with a 1000 w your getting alot of depth in regards to penetration. Almost be a shame. Well a waste of light anyways, I wouldn't lollipop the plants at all if I kept em small. At the end of it, now that my mind is working a bit better to get what you really want from this is to veg under 400w low numbers and get em big. Rule of thumb with when you should harvest... when you think they are done wait another 2 weeks,lol. The swell at the end is what its all about! I'd set my sights on 9 weeks min without checking the trichs. but now if they were mine I would check them obv. this is just a ballpark. As for curing, depends on the genetics, some cure out nice and quick while others are still gooey in the jars. I've had some where I couldnt seem to get them dry. Mths after harvest still gooey when im breaking up buds. And I let them hang like 18 days after cut in the room. Either way, hope this babble helps you out. Whatever you decide, even if you get a 400 watt. Put the 1000w up a bit more just to be easy on the girls. All the best bud.