you can save 2-3 weeks of vege time or more by doing sog. this won't save as much as shaving 2-3 weeks off the end when the lights and all equipment are running significantly harder than the first few weeks, but it's still a good chunk of electricity.
more pots can be more hassle but likely similar volume of substrate, just in smaller pots.
Think your light is about perfect. 800-850PPFD (rough guesstimate of total power) over 12 hours will give you upper range of DLI, so in ambient co2 this will maximize yield from your 70x70 tent.
The cost savings are minimal so do what is best for you? if variety is king, do a sog. if you don't give a fuck about variety do 1 plant, lol... nah, i'd do "4" just to have some risk-protection, and if not buying too expesnive of seed, plant 150-200% of what you need so you can cull the weak.
if it's a trusted breeder, i'm sure you'll get quality plants. I can't tell you who to go to. i've tried a handful and even those with good reps have duds. plus, you never know waht they actual genetics are. "GG#4" might just be some gg4 clone they bought from god knows who then bred with their own genetics, and still labeled as GG4 when they sell it. no oversight, no protection.. they can say it's a "landrace" but may not be true etc etc.
i wouldn't worry about labels. i'd worry about the traits you get that matter - flavor, potency, whatever you care about. the names are all wishy-washy.