I don't know this ISP, but don't forget there is a difference between backhaul and the actual ISP network. AAISP use TalkTalk and BT Wholesale for backhaul but run their own network.
I wouldn't go to TalkTalk for ISP services, but I would have no problem using an ISP that used TalkTalkBusiness for backhaul.
That is if my Openreach line performed well enough for my needs. 
I know there is a difference, but I don't really want to give Talk Talk any of my hard-earned money, I have had to deal with the company and I have also seen how they tried to slam a mate of mine by trying putting him on their network when he did not ask. Sure it may be the retail side that did that, but I still prefer to stay clear of them
Saying that I am not a fan BT or openreach, even if I am with plusnet, at the time I needed broadband for a decent price and I did not have much time to look around, so plusnet it was.
But to be honest they have been pretty good, but I did not really want to go back onto the Open reach network, but had little choice.
Adrian
Desktop machine Ryzen powered with windows 10 , reluctantly.
Plusnet FTTC