There have been a lot of changes in the H-16 since it was introduced in 1970. I don't think any one of them could be considered significant, but collectively, they are.

Superficially, a 1970 H-16 would look the same as a 2006 H-16, but they are different boats. The 2006 H-16 is much lighter, has better made sails and parts, and the mechanical things work better (travellers, blocks, tiller connectors, rudder lock-downs, rudders).

There's been a lot of refinement in 36 years.