All SynthV products sold by AHS except for Hanakuma Chifuyu (their latest release) are currently 20% off on DLsite until January 10.
If you have any coupons, you may be able to use them in addition to the sale discount. All products are digital download versions (no physical boxes). This also means there is no Pro + voice bundle, since AHS’s bundle is physical-only.
In addition to SVDs developed by AHS, this also includes:
The software is the same no matter which store you purchase from, and yes, the software supports English. The language warning on DLsite is a generic one displayed for all software products, not specific to SynthV Studio.
Updating is done from within the application; see the “Updating your products” section of this guide for instructions.
…and it will grow over time. Synthesizer V Studio have the most realistic English sounding synth voices I’ve ever heard even when using just the free Basic edition. If buying AI voice banks in Asia Region, AH-soft looks like have more to offer than DLsite.