I recently noticed a discrepancy when trimming extruded surfaces, using another surface that I thought was symmetric. After further investigation it appears using ‘normal to profile’ in boundary surface, in conjunction with 100% tangent influence, can lead to unexpected results. After conducting some more testing (and checking in Rhino) it seems that extruding the profile then using ‘tangent to edge’ gives the expected results. This is probably not applicable most of the time, but good to know about!
