HTTPS is currently only accelerated with TFO (no compression or AO) in WAAS 4.1.1 and before. HTTPS support is being introduced with a Application Optimizer in the upcoming release WAAS 4.1.3. 4.1.3 will allow optimization past TFO to include Full Optimization, etc.
Look for a late March release date with more information on the HTTPS AO as well as Scaling information at that time.
The current scalability numbers can be obtained from your partner and/or sales team, which would probably be the best way to review all the models.
Thanks,
Dan