Ok here a couple of facts
1/ the 55 verus 50, the rocket is 7klm out stock when I put the 55 Car tyre on it was only 2 1/2 - 3klm out the 50 car tyre is 7klm out so the 55 bridgestone will be about 2 1/2 to 3 klm out but remember correcting the speedo put the odometer out
2/ Ehh from the .com site had them on his bike earlier this year in Tassie we had three days of crap wet weather and while he did say it was a bit twichy at times he wasother wise reasonablly happyand said they were better than the metz(that wouldn't be hard), the darksiders had no complaints, except one darksider running a metz on the front lost the front and went down when he panicked and grabed a handfull of front brake while avoiding a fallen Victory rider, I was able to slow down and avoid the two fallen riders while towing the 450kg camper and this was on a downhill corner in the wet, I had my dangerous

car tyre and Shinko controlling not just the rocket with two on board but towing an unbraked 450 kg camper

I'll stick to the darksider with Shinko on the front
just one more comment from the guy who told me about the Shinko also sells Bridgestone to the Racers at the National Superbike races and recomended the Shinko for the front as the Front Bridgestone was in his opion NOT up to the job on the Rocket but said the rear Bridgestone would work well with the Shinko front while was anti Darkside I would otherwise not doubt his advise as he advises ASBK race teams on tyre selection he just could not get his head around the darkside thing and was amazed when he saw the well scraped pegs
I hope this helps, oh by the way Ehh lives up your way Mitch and I found him not to be an agressive rider