Been with Xilo for years, on ADSL2 (C&W LLU) and now 80/20 FTTC.
Connection has always been reliable, routing seems ok and they (Matt) are very quick to reply / carry out changes. I've dropped in support requests midnight at the weekend and had replies ten minutes later.
Do expect some things to be manual that may be automatic with other ISPs however there is a nice personal touch
Never really had any slowdowns on ADSL2 but only 4mb sync...Now on FTTC I sync at 60/18 and can go full speed anytime of the day, any protocol. I do however have the top package with higher AR and priority (FTTC 125gb+ or something, it is not budget)