Thanks for the feedback.
I was initially thinking the same but when I asked the guys as GN, their response was:
"We would typically recommend a Telos-0010 to replace a budget 600W HPS light as the Telos-0010 can produce better quality and produces a similar yield.
We would also say though over a 1mx1m space the Telos-0010 is the best light you can use with photoperiod plants however if it is for auto flowering plant the Telos-0008 might be best fit depending the hours per day you are running."
I think I'm gonna take your advise and go for the 8 though. The initial saving would be helpful and long term would keep things more manageable. I guess it can always be supplemented if need be, though i doubt that'll be the case. Clearly you're having amazing results with it!
Thanks again, feel much more confident about hitting that order button.