Mounting Bindings using Ball of Foot method

[ultradonkey]

I changed bindings on my old alpine skis and now they ski like I'm standing on the tails. I figured out that one difference is that the 'new' bindings are farther back on the ski compared to the originals. I am now on the manufacturers mark whereas before I was approx. 1.5-2cm forward. So I am going to remount them using the BOF method, but it would bring the bindings forward 5cm! This seems like alot to me and I wonder if this type of change is common. Is there anyway to pinpoint the exact best location, or is this just a try and see kind of thing? The skis are Atomic R:EX, and it seems that Atomic is known to put their boot midsole mark quite far back. I don't want to overdo it, and I'd like to find out what other people have done in similar situations. Getting the bindings forward, even a little, seems to really help me.