I watched the Optimum disc (twice!) and it looks stunning.
The inserts are hardly noticeable and there are only 2 short sequences in Italian with subs when watching the English dub.
The audio is also very pleasing.
I'd say the English dub is my favorite (although it differs somewhat from the Italian)
A really good giallo with a great cast and some fantastic eye candy (especially now it's largely been mastered from the negative).
A fantastic job by Marc Morris!