A 600spd player is not running out the bulk of the time. Odds are you going to get at least one trip to the table per rack if not more so don't play scared.
A moves game is generally the last skill set that's developed by players. So although you could expect to see a 600 player kick out of simple safeties you can pretty much bank on them not returning it to you afterward. That makes playing slightly tighter a good option to develop easy opportunities for yourself, and it can quickly throw that player out of rhythm. That said, a 500spd player will not have a great CB, so you need to pick your spots carefully when playing safe.
I've been under performing for a while now (maybe my new norm) and hover around a mid 670 w/ ~600games in the system. I find I'm in a spot that regulates me to 'open' events, which means I can frequently run into players that 50-60pts higher than myself. In this world you are fortunate to get a look at the table, and often you're sitting for a rack or two if not more. Do I play differently when I run into >750...? Well it's only happened a couple of time but yes I do.
A >730 spd player will a decent/strong moves game. Combined with a strong understanding of kicking safe, or into unfavourable situations for their opponent. In short, my usual advantage now has me as a dog in this game. So although I don't dismiss safe play, I do tend to lean on shot making a hair more. My only hope is to keep pace, and try to place some performance pressure on the stronger player. That means I need to take more chances rather than duck'n'hide.
The people who write "Play your game, don't play your opponent" are correct to a point. The problem is that it's easier said than done.
You should pit (play) your ability/skill against the table. Your decision making should be weighed against the ability of your opponent. IMO, those things are mutually exclusive.