You should use the img tag (in [] brackets) to present images; I'm sure you could do that with the PNG. That way we won't have to follow your link.

Sorry if I'm going to sound negative, but we get a bunch of those YAKL (Yet Another Keyboard Layout) newbs in, wanting to improve without having grasped the finer points or done the proper analyses yet. Heck, I was one of them myself, back in 2006. ;-)

My advice would be to change as little as possible. So, your B sucks, you've moved the M and Y pretty pointlessly etc. Tradition with German layouts, well... maybe. I abandoned the stupid Norwegian "traditions" and have been happy about it, because it allows me to type better in a world very influenced by the US layout. But in my case, that only concerns the symbol keys and your choice is about a letter. Well, think it over at least. :-)

For D and H, also consider my milder DH-mod if that's easier to fit in with the rest. I think it's every bit as good on a normal-stagger board but of course not on a matrix board (which I don't use anyway).

If it were up to me, I'd do the DbgHk or DvbgHm DH-mod with the ANSI Angle-Z mod instead of all that milling around, banning Z to the old B position. Since you want to move the V, maybe SteveP's DvbgHm mod is best? Or you could go for the hybrid DvbgHk if you're so inclined; it's less supported but quite doable. I agree that the QWERTY-T/Cmk-G position is inferior, but it's plenty good enough for B – especially when you have the proper CurlAngle hand/wrist positions!

Then, the rest reduces to äöü which I'd put in the middle using a Wide mod but if not then keep them in some of the symbol key positions anyway. That's very decent, and compatible with the rest of the world so you don't get confused when moving to other keyboards.

As you've noticed, putting a key somewhere else will likely mess up some bigrams (as with the Y in 'you'). In fact, Colemak excels in bigram stats so it's hard to come up with something that improves this important measure. Hence, you're almost sure to mess up something that'll come back and bite you in time but you may not notice it before you've learned this so well that you don't feel like fixing it. Word of warning. ;-)

My position on ISO vs ANSI is well known. Furthermore, for us International users, I think it's a no-brainer really. We simply need that extra key to accommodate all our special letters.

What you've got there is SteveP's DvbgHm mod; the upper one is with the ANSI-Angle-Z mod and the lower one the ISO/main variant. I agree, this is a solid option if you prefer the QWERTY C/M positions to the QWERTY V/N positions.