I love S3D, but I've found something I'd like to see 'borrowed' from some other products: additional infill patterns.
As a minimum, I would like to see a more 'rounded' option that doesn't require jerking motions on fast prints. For example, something akin to an 'S' or '8' shape (see attached) that loops back and forth. Again, based on output from other products, I've seen this patter work really well. Both concentric and rectilinear fills have their purposes, but I'd really like to see this one.
-Jason