The 19s need a little extra slip on the launch. They're great on the slab, but put a noticeable & audible strain on the mill at under 3500 RPMs.
I too went to an 18 from a 19, but I also don't expect to do any long slab trips in the near future. If I had a lengthy slab ride on the horizon, I'd put the 19 back on. After the first time you swap the front sprocket, subsequent change outs can be done in around five or 10 minutes.
To each his own I expect.
