I done that window reg hack along time ago to get those extra MS voices, but ultimately their not very good.
If anyone is looking to buy some good
x64 voices.
Open SAPI5 voices that can work both as windows default x64 and any x64 app.
I think the best x64 voices (open sapi5 to work as default windows x64 voice and any other x64 app) are really only the ones from IVONA, and AT&T (
Buy +
Demo), and then this other company called Cereproc. I've searched the internet and there are none better in my opinion than IVONA and Cereproc, with a 3rd place by AT&T.
There are two others in the top list Nuance (really good), and Acapela but these two
only work with the partnered software from Nextup.com , and are not Open SAPI5 which I mentioned above you need in order for x64 bit voices to work in other windows x64 apps like Voice attack/teamspeak x64 etc. Although I've not tried this to see its wrong, not without buying them.
AT&T are ok, but my favourites are
IVONA and Cereproc.
Cereproc
https://www.cereproc.com/en/support/live_demo (demo at top of page)
IVONA
http://www.ivona.com/en/voices/
Cereproc do very good Scottish and other UK accents. Still not quite as good and clear as IVONA, but for the cheap price they are £25.99
https://www.cereproc.com/en/storesapi are good value I think.
I do like the Scottish Heather voice. And there are many other 'moody' voices like the Scottish Dodo one, and Scottish Stuart is very good. The Irish ones, and Sue English 'black country' accent. You can hear the different accents. Good to have this many to choose from so you get your perfect AI voice, or buy a few and chop and change them.
And if you want a J.A.R.V.I.S. from Ironman, then the cereproc 'Giles' or 'William' are pretty good 'English butler' voices.
In fact for English 'English' and 'Scottish' voices, the cereproc ones do have more life and personality in them. I like them. And for windows reading back to me, I've just bought IVONA Indian English Raveena, and a couple from cereproc. I plan to use VA for some time so feel happy to pay for the voices, lifetime licences and upgrades remember.
Both companies will most likely give you a 10% discount if you email them first. cereproc voice are a little cheaper, maybe not quite as clear as IVONA, but they have more regional US/UK accents which is fun.