I have owned them both, although not at the same time. Overall I prefer the Perseus, but I did have it upgraded by Mark O'Brien with about $500 of internal goodies.
In my system, the Perseus is more neutral, much more transparent and dynamic. The 99 seemed to have a mid-range tube glare that I could never get rid of even with various NOS tubes.
Send me an email if you want more detailed information.
Regards,
Dave