Betfair CLV: 'safe' CLV?

Hi all, I’m helping some people become more profitable gamblers (have suggested this service: no bites yet!), and we’re considering integrating some Betfair exchange bets into our pooled ‘syndicate’. Since I’ve been doing this, I’ve been quite lucky: 28 bets placed on Betfair exchange, 899 turnover, 99£ profit. However, I had a look at the CLV and it’s -1,8%. I was wondering if we know of a CLV% that returns more +EV bets at closing line than not when factoring in exchanges? Or perhaps exchanges have a more profound relationship with TTS, and so I should reduce this instead? Even if, say, a 4.7% and above returns 0.1 CLV on average, it’d work for us as an educational tool. Not worried about losing bets below this magical rating.

It is difficult to get in on +EV bets on exchanges since you are competing with betting bots.