Glad someone stopped to help you
Read what you like into whats below but it's not meant to be condescending, just my views and experience
If you're doing 600 miles a week on tarmac then you need a road tyre as you've said. A GS isn't a sports bike and will only go so far over before something (rocker cover, peg, centre stand etc) digs in and off you go. How grippy a tyre do you need? I can't see the advantage of 020's on a trail bike

I had rennsports on a zx7rr and they were the cats t!ts on a hot day after 15 minutes balls out riding but a nightmare any other time.
Realistically what do you need? On the Escapes and tourances I had on my 1150 I could scrape the pegs and hoon around on them in reasonable confidence however the tourances did sometimes "snap" the escapes didn't.The escapes felt the better tyre
I know it's not the most practical advice but if you want to learn how to really throw a big trailie around, buy a little one and play in the dirt
You'll soon learn how to power slide, correct understeer and all the daft little things that can have you off on the road and it'll improve your confidence tremendousley