Well since this is such a grown up conversation and nobody is comparing willie sizes I think I'll put my situation up to see what everyone thinks.
I've just bought a 1.2m x 1.2m x 2m tent and I'm planning on doing a semi-perpetual grow by using my original .75m x .75m x 1.6m tent to get them to 4 weeks before moving them into the bigger bloom/flower tent where I'll have two GT205 NFT tanks running at different stages. I could use bigger tanks in the new tent but not in the old one so I'll stick with the smaller ones for now. I'm basically investing a bigger tent etc. so that I only have to grow for 6 months a year instead of 12 to remain self sufficient in good smokes.
So that works out that eventually I'll have 3 GT205 tanks running with two plants in each.
The lights I've got atm are all Vipars - A V240 which is perfect for the smaller tent for the first four weeks which costs around £70.
That leaves me with a 400w COB, a V300 panel and a 165w flowering panel which all cost a total of £340.
This is where my conundrum begins, the COB is fine for sitting in the centre of the big tent providing useful light to both sets of plants, the V300 is fine for directly above the 4 to 8 week old plants and the 165w flowering panel I will only be using for sidelighting the oldest 2 plants.
If you've managed to follow all that you'll see that I'm missing a light to put directly over the oldest plants, the obvious solution is to move the predominantly red spectrum COB over the top of them and buy a GN HS1 light for dead centre in the tent. 4 weeks ago I wouldn't have dreamed of spending that much on one light but I've seen that the HS1 can flower too now(thank you TaNg!).
I've got the money saved for one (or 2) HS1's but I'm still inherently cheap. I go for bang for buck in everything but I use expensive intel chips building pc's because they are by far the best on the market and the HS1's are blatantly the led equivalent of intel so I'm left with three acceptable options to me;
1. I bite the bullet and go for 2 HS1's in the big tent and trust in science for a hefty £800+!
Downside for me is the cost and also I might not manage the best yield from 4 plants under just 2 lights. Upside is the very low power consumption and noise levels.
2. I buy another Vipar for £100 and fit expensive but silent PC fans in all my Vipars for another £200.
Downside is that I'll still be drawing 800w of power and even 5 quieter Vipars will be way louder than 2 HS1's. Plus I'm still stuck using older tech which rarely happens to me in anything else. Upside is the cost of £300.
3. Buy one HS1 to replace the V300 and keep on using the stock Vipar COB in conjunction with the GN until I'm confident enough in the GN to get another one and all the extras to make my grow a fully GN one. The down and upside to this option aren't so bad, it's an extra £100 on option 2 but I do save some power and lower noise levels too.
Now I've got to take into account that the Vipars have paid for themselves many times over in that I haven't had to buy any smokes this year, so my first year growing has cost relatively little initially and with the bigger tent I can halve the amount of time I'm growing for the same annual yield still using the Vipars.
If I was just starting out or switching to LED I'd likely buy HS1's but it's hard to see a great need to reinvest when I've got lights that do the job.
Unlike the world of computers, where new software needs more powerful hardware there aren't any new seeds out there that need HS1's to grow so as much as I want the new tech I don't need it unless there is a compelling reason to get it, this is what has stopped me clicking BUY every time I've got tempted!
So what would you all do?
Well done Bilbo, exactly what I was talking about. Option 3 would be my choice were I in the same place as you right now. You have experience with LED growing, you already understand the benefits of spending the extra money for the quality you desire. Intel vs AMD etc... or GN vs Vipar. Option 3 allows you to bridge the gap between the 2 without going all in on GN HS1's all at 1 time. I envy you, you have the time investment behind you that I have just embarked upon. I will probably (as history shows) acquire several different LED units before making the leap to the HS1'S or maybe by then, GN's next generation. But again, I believe option 3 is the most prudent course of action. Spend some money, save some money, get a new toy and GROW ON.