All Echo's are commercial grade. That made me laugh. The pB-251 is junk. Open it up sometime and tell me that is quality. Looking at a label that states emissions compliance doesn't tell the quality of the unit. That's a ridiculous statement. BG 55 is better built, produces more power at a lower weight and a lower price. The pb251 is just rated quieter, whether it actually is, I couldn't tell. It's a POS Home Depot special. ECHO is sacrificing quality to meet Home Depot's price demands.
People need to be aware that ECHO's 5 year warranty is for CONSUMERS only. If you are a professional, then you will get 2 years. Also be aware that long extended warranties are marketing gimmicks. If a unit is truly defective, it won't take 5 years to show up.