Are sub-$300 inflatable paddleboards actually any good?

For flat-water recreational use, yes — multiple high-trust r/Sup threads acknowledge that budget iSUPs like ROC and FBSPORT are stable and durable enough for beginners, families, and casual lake paddling. The trade-offs called out repeatedly are lower PSI ratings (typically 15 PSI vs. 20+ on premium boards), basic aluminum paddles that most owners eventually upgrade, and shorter warranties. They are not suitable for surfing, fast touring, or rough open water.