Cant comment on the king but fork rake wont differ much if your going from a good brand to another. The only massive difference you'd notice would be if you had something like onza forks (they have a massive rake) to something like a set of echos. Even then the difference would be for the better and would improve the ride. All in all I'd say not too much difference, and you'll be used to it in half hour
Rain king half tread £20
Der Kaiser 90% £35
I'm tempted towered the kaiser just for the longer life? Do they use the same compound?
What about pinch resistance?
May seem a bit silly, but watch Kevin and Perry go large, Has loads of dance/cream music in a may well be what your looking for, if not its funny anyway!