RE: acid or kombat
Its always hard to decide how big a quiver one should have. I would say that if you have the money and space, you will no doubt have a quiver with boards whose sweet spots cover a bigger range if you add the 05 A74 to what you have now. The 74 will work very nicely with 5.2 and be a blast with 4.5. The 05 Acid 74 is a great board btw.
The Kombat 87 is indeed a great board and I would say its a fair bit nicer than the Kombat 95. At your weight it will carry a 6.0 very nicely. So it will be a good replacement and definitely work much better with both 5.2 and 4.5, but it can still not compete with the Acid 74 in high wind.
So, what you have to do is try to make a choice. The K87 will give you slightly better feel in you sailing overall compared to now. The 87 is simply a better fit for you. But it can't do miracles with a powered up 4.5 and since you do seem to like the 95 (which _is_ a nice board too), the "add an acid" route seems like the best choice. You always have the option to update the 95 later.