Agreed. 70W HPS would be OK for 100W MV but not for 175W MV lol. One utility in RI used 70W HPS to replace 100W MV but the other (and larger) utility used 50W HPS. The 50W HPS is pretty dim but 70W HPS is about right. A brand new 100W /DX MV lamp appears slightly brighter than 70W HPS but the lamps quickly start to dim out so after a year they're about the same. A clear lamp probably starts off the same as 70w HPS. Occasionally I see 100W MV replaced with 100W HPS here. They do that so they can still bill the city for the 100 watts lol.
Duquesne Light used to maintain their mercury vapor street lights until 8 years ago. Now if a mercury vapor fixture needs a lamp or photocell replacement, they'll just replace it with a high pressure sodium one.