Our brands are different in the US than what you have, but I will offer some advice...
1. Probably the #1 thing is that it's not really your decision. No matter what research you do, and no matter what recommendations you get, and what you "decide on", the all-important vote will be his, because yes you want his food to be as nutritious as possible, but even more important that that, it needs to be something that he really likes! (and that it agrees with him).
2. I definitely would not rule out foods just because others say it disagreed with their cat's stomach. That's kind of like saying I don't want to eat peanuts because others have a food allergy to it. What matters is how YOUR cat reacts to it.
3. It really does pay to have 2 or more dry foods that he likes really well, because many cats will go on and off foods all the time. It can be maddening, but I suppose if someone were to feed me pizza every day for every meal, I'd eventually rebel to that too, so I guess I can get that.
4. I really wouldn't mix foods unless you have to. And I think the only time when you really have to is when you are transitioning from one food to another. The reason why I say that is the whole going on/off foods thing. You may be biasing him against *both* foods on any given day.
My advice is to initially do what Sherry said, and keep him on the breeder's food for a few weeks, then select several different brands & flavors that you think meet your nutritional criteria, and buy really small quantities of those (if possible) and try them, knowing that some of them you will end up tossing out (or giving to a shelter).
This is a good article to check out:
http://www.littlebigcat.com/nutrition/s ... -pet-food/