We've already seen it. It is just a spyware filled bootleg of T3DE.

What's the worst that can happen, aside getting banned?

The default official IMVU client is full of spyware that steals over 120 different pieces of personal information from your computer; including name, address, phone number, IP, hardware ID's, and software keys. IMVU inc sells this information to third party marketing companies. They also use this information to track users between multiple accounts. This tracking allows IMVU staff to ban you across all past and future accounts if even a single one of your accounts does something wrong.

When we, the mafia, make custom IMVU clients ... we carefully and lovingly take the time and patience to remove all of that spyware, keeping you and our other users SAFE. However, we have not seen anyone else yet who takes that time to remove the spyware ... either because they don't care or they don't know how. The T3DE bootlegs fall under this category ... still full of the spyware, which in the best of cases will simply steal and sell off all of your personal information. In the worst case ... it can allow IMVU staff to track you down between all of your accounts ... to the point you will have to change internet providers and buy a new computer if you want to play IMVU after getting caught breaking their TOS.