I use Cisco LR 1.5 & 1.8 atty's. I have a couple of Robs EM 1.5's and they also work very well. My HH.357 sits for a while, still looking for a good juice for it. Also have a couple of Cisco 306's.
I hope someone chimes in on a 901 and its use on the REO. From what I have read they produce excellent flavor and vapor. My cost issue would be using a drip shield and adapter, don't know if i would also need a 901 specific drip tip.