Ultrac Sesstanas are being discontinued - although you can still get them, but as stock dwindles and you were unlucky enough to ruin a single tyre sometime down the line a direct replacement might become difficult, if not impossible, to source.
And yes, you have read lots of opinions about which tyres to use and MPSS seem to get the biggest thumbs up, particularly by those I know on here like to push their ZEDs to limits, which is alwaya a good indicator, for me. That said, many others, including myself, have found other brands up to the job for normal road use and spirited driving.
The more critcal factors from the years I have been reading members' findings, including some sad outcomes, is to have all 4 tyres the same; regularly check pressures and don't wait until you get down to the legal limit for replacements as the combination of + or - 300bhp/RWD/wet roads/and a leaden right foot will mean you will end up not facing the direction you had intended to travel.