The plow may be fine, but the trip feature is worthless:
1.) You don't need it.
You're not going fast with the rear plow down. You aren't going to strike any curbs or large obstructions. The cutter edge faces straight down or slightly backwards that skips over small obstructions like man-hole covers, etc. The rear plow gets it's ability to clean from downpressure, not from cutter-edge angle like the front plow.
2.) It doesn't work anyway.
Most pull plows have side plates that allow you to carry snow. The plow won't trip with these side plates touching the ground. Snowman gets around this by having the sides go part of the way down and rubber the rest of the way. This leads to snow not being very well carried.
3.) They increase maintenance.
You have another pivot point and 4 springs to adjust.
4.) The design adds weight without strength.
The plow arms must come over the top and down the back of the plow. These arms are very long and must needs be made of heavy steel. They're way longer, heavier and not as strong as arms that connect to the front of the plow. Besides most significant damage that comes to the rear plow is from guys backing into things, which the springs wouldn't help anyway.
I've plowed with rear plows for 20+ years. We had a local manufacturer that used to build spring trip rear plows for a few years, they were good plows but the spring system was worthless.
I like the Snowman snowplow, but the spring trip design feature is for sales purposes only.