Well easthampton here in the western half of the state originally said they were only replacing the streetlights downtown with LED. they eneded up replacing every cobrahead with LED and now are looking for a post top LED to finish off all the HID lighting in the city. MORE than likely boston will end up replacing most fixtures out to LED, it's just a matter of time.
in my city mercury stuck around alot later on residental streets than the arterial roads....in most area's of my city 175 Watt bucket nema's still light up residental area's and most still work.
Personally I would just get some 70-100w MH ballast cans and some 3000K CMH lamps.