Is 16GB of DDR3 RAM still worth upgrading to?

Yes, 16GB of DDR3 is usually worth it if your system isn’t too old. A used 2x8GB kit costs around $30-40, and the jump from 8GB to 16GB is noticeable since browsers alone eat 4-6GB now. Just make sure your motherboard and CPU can keep up – a Core i5-2400 or similar is fine, but a Core 2 Duo or low-end Atom will bottleneck you. Don’t overpay for fancy heatsinks or RGB; just get matching 8GB sticks.