Ian,
While your question is about ramp in rates I think there is a lot more here to consider.
I assume you are talking 3" to 6" long sides in 4/4 and/or 5/4 material. Also since you are referring to parallel edges I'm also assuming you have multiple rosettes next to each other out of a single wide board. Is this all correct?
If so then the questions are:
1) What diameter bit in relation to the space between rosettes? Is the bit edge touching side by side rosettes at the same time or is the gap between parts wider than the bit diameter? If wider, how much wider?
2) Upcut or down cut spiral bit? Upcut will lift the parts while downcut will compact the chips in the cut slot which will help to hold the parts in place.
3) Are the rosette corners blowing out when they are not lifting as well as when they are getting lifted off the table?
4) Are you making a full depth cut in one pass? Is the roughing pass full depth or onion skinning? Is the finish cut in one full depth pass? Is the lifting taking place on the roughing pass, finish pass or both? Have you tried tabs on the roughing pass if that is going full depth?
5) What is the hold down system? Bleed board hold down with typical rosette sized parts is actually looking for trouble. Custom made gasketed true vacuum fixtures would be a much better system. The caveat here would be that there could still be room for side shift issues with the small parts.
6) What size blanks are you starting with? 8' long boards for example or 2' to 3' long blanks? Could the blanks themselves be vibrating/shifting and thus adding to the problem?
Lots of questions here but generally I'd say you are on the right track with slowing down the feed rate. However I don't know if changing the entry drop angle will make much of a difference one way or the other. I'm assuming here you are talking a z-drop entry angle vs. an x,y side entry angle.
Also the bit design can have a big impact on this both from the perspective of upcut / downcut and the shear angles of the bit edges. You might find it useful to talk to your bit manufacturer to see if they have any recommendations.
BH Davis