Sherwood Blizzard has been a workhorse reg of the dive industry for year but from a performance standpoint there are better regs available. In the Sherwood line the Maximus and SR1.
I Started diving using the Sherwood Oasis which is the warm water version of the Blizzard. I’ve since moved on and now use Oceanic Delta IV FDX10 regs. The FDX10 is an environmentally sealed reg and as such is rated very highly for cold water environments. Beside the Delta the FDX10 first stage is also found on Oceanics top of the line EOS reg.
There are many other brands that offer regs with environmentally sealed first stages but I’ll appeal to you to only consider those from manufacturers who’s pricing structure is MAP and eliminate those with a MARP structure from your choices.