As a follow-up to the those interested in my experiences with NB's rye malt syrup. I made two, 2.5 gal batches with it; one was a rye stout and the other a rye porter. The stout turned out very nice; dark, pleasant graininess and slight bite from the darkly-roasted grains with a dry finish. I really can't say, however, what the rye is contributing. The porter is still in the secondary awaiting the addition of oak chips and rye whiskey, but the samples I've drawn show it to be a good, complex porter.
So it is worth a try, but note that the color is quite dark.