I used the HP for some time but I do not use it in my current hardware configuration. The one I have is an original model of the 60s, not the Italian edition. I do not know if there is a big difference, but I have heard that the new were also very good and in the same spirit. All that to say he had "done" well "oiled" and that nine risk of sounding less well at first.
I tried many HP fairly standard (Celestion, Electrovoice, Emminence, etc ...) but I have used it in a Fender Blues Deluxe combo, so this is the only context in which I know really good (for lack of time and priority in testing gear)
It was perfect for this combo Fender, especially because he did not exaggerate the bass, which are often too large and too intrusive for my taste on Fender amps. It is also frequently recommended with this brand of amp.
It also tended to slightly compress the upper midrange and gave them a beautiful color from the original HP Emminence. This allowed also to bridle the famous side "slamming" of these amps without distorting the sound. Crunchait it a little easier too, but it was still perfect for clear sound (for those who - like me - do not like the sound crystal clear and cold of some modern amps)
In short, I appreciate it very much and I've always intended to see what he could give an amp with English ones I prefer (Marshall, Hiwatt, Orange ...) If I do a days, I will attest.
Attention, it has only 50 watts while, unless used with an amp under 50 watts or pair it with another HP, do not push it too.
In my memory, it is not too powerful (97 or 98 db I think).
I'd be curious to compare it with a new one.