Both systems deliver 600 GPD tankless RO. The G3P600 adds NSF certifications the G2P600 doesn't hold, more filtration stages, and better verified performance. Here's whether the difference justifies the price gap.
The G2P600 is a budget-tier system. The G3P600 holds NSF/ANSI 42, 53, 58, and 372 certifications — the G2P600 holds only NSF 372. For a drinking water system, the performance certifications on the G3P600 provide meaningfully higher confidence in what's actually being removed.
NSF 58 is the core reverse osmosis performance certification. It requires independent laboratory testing to verify TDS reduction across the rated filter life. The G2P600 lacks this certification — meaning its TDS reduction claims are manufacturer-stated, not independently verified.
For a system you're relying on to remove lead, fluoride, PFAS, and arsenic from your drinking water, independent verification matters. The G3P600's $80–$120 premium buys you certified performance.