I have bought 3 pieces. I am using them from time to time usualy as backup amps.
1. First of all is the price. Maybe the best at this performance.
2. Second, got better sound results in 4ohm and 2ohms than in 8ohm. Is not about more power, is about better response, higher voltage, more dynamics. The user manual states can bridge it in 4 ohms. Works.
3. Third point you need to manuly set your crossover after the RTA setup. It can nearly match better and expensiver amplifiers.
Overall is a cheap and enough quality backup. Can not say about reliability since i am not using them enough. I will ad that i had to push them some times in 2 ohm and bridged 4ohm near to the max for 8-9 hours and what i got was a reliable sound, good cooling. I am satisfied