There is a big difference between a basic and a Herpstat 4, a much better comparison would be between the herptat 1 and the herpstat 4.

A herpstat 4 is literally 4 herpstat 1's in a single box. it is more cost effective, and each channel is electrically isolated/fused. There are a few parts that effect all 4 channels, but for the most part a failure will only effect 1 channel.

The herpstat 4 is the most cost effective option, and is just as safe as using 4 herpstat 1's. The Herpstat basic is actually less safe due to the lack of a few key features.