R’ Hamburger identifies 4 different pronunciations of the cholam.
1) Poland and Hungarians pronounce komatz chirik (as in toy)
2)Litvaks and Russians pronounce segol chirik (as in pay)
3)Dutch Jews pronounce patach shuruk (as in how)
4) Western Europeans and Americans pronounce komatz shuruk (as in go)
It seems that the yeshivishe nowadays all pronounce according to the Polish way, in an attempt to ape their peers and appear as “frum” as possible.