There really isn't just one cutter for every job harry, I wish there was.
Basically, Rubi's are classed as one of the better cutters money can buy, but your paying for a well known brand name too.
What you really need is 2 cutters, a smaller cutter for everyday kitchen splashbacks, now I still use a very cheapo Plasplug dry cutter, only cost me £40 and that does fine for everyday ceramics upto 400mm, then I have a Husqvarna TC670 600mm cutter, basically aimed at the Rubi brand but half the price, and that does brilliantly for the bigger jobs that a smaller cutter can't do.
Why you might ask don't I just use the Husqvarna for everything, because it's a big cutter, not something you can work with easily in a small bathroom, so that's why you generally have atleast 2 cutters, small and big, many have 3 or 4 or more as they go along, same with wet cutters, have a small wet cutter for small jobs and a large wet cutter for the tiles that are too big for the small cutter.