I several minutes ago purchased the two new voices for the Blastbay TTS engine, and I'm very impressed with it. It is a hybrid engine (combination of neural and formant), has two American English voices, a male named Richard, and a female named Libby. Libby is my favorite. This synth is both 32-bit and 64-bit, is SAPI 5 compliant, and has a sample rate of 48 kHz. It's very responsive with NVDA, and it can go very fast, even without using rate boost (I never use high speech rates, I just keep it at default rate values for all of my speech synthesizers I have, for consistency reasons). Each voice costs $19.95, and it uses the classic email and serial number authorization method. Note: when you try entering the serial number during the installation, the is a password field, so you will hear ***... in NVDA.