I've been running the snapper/dart using the dart impeller for a couple years and this pump has functioned great for me so far. The decision on whether to run the snapper vs. the dart depends on the size of your tank, head pressure, additional equipment tied in, and the type of livestock you intend to place within your system. I've run an Iwaki and blue line in the past and both of those run louder and warmer to me. I know several other people that run various Reeflo models with exceptional results. Extremely quiet and durable. From what I understand they have great customer service as well. i.e. I'm happy with this brand.
Note: The Iwaki and Blue line operated well and I still have the Iwaki as a back up.
I have the Hammerhead Hybrid on my 465, and I run the Barracuda impeller (less flow), and I still have it valved down about 40%. Great pump, but not quiet by any means. As loud or louder than Pan World pumps, as I run both.
I run the snapper/dart hybrid with the snapper impeller for my closed loop. I also run an pan world next to it as my return pump. The pan world is slightly louder. I bought the reeflo new, but the seal was bad from jump, but their customer service was exceptional and the problem eventually solved.