We have a lot of clients on LVX at IB. I have a few. Waiting to offer it to our Wedbush clients so we have more control over service/support and pricing.
As to why more do not use it, it is an option centric platfrom that focuses on option analytics. I personally prefer CBOE Silexx for trading but Silexx does not offer the analytics, yet. When I has an Option MM, I used LiveVolPro as a third party tool.