It sounds like the same situation with a Rousseau mounting plate; a very slight crown is there for a reason. It ensures the wood passing the bit is always at the same cutting level. This feature is designed to accomodate uneven wood surfaces. I have seen reports from people who claim it is impossible to get a good cut with this set up. To this I reply: I have a couple and have installed them for friends. We seem to be able to get precission cuts with no problem. Norm Abrahms used a Rousseau plate in his NYW table for 10 years until Rockler sponsored him. Trend-UK sells a licensed version of this plate with their name on it. I have seen magazine reviews stressing that your mounting plate must be perfectly flat with one exception, the Rousseau plate. I can not speak to the amount of bevel in your plate, but if it is a tiny amount then give it a try. Your results will speak for themselves. Let us know how this works out.