We have close to 10k tickets in the last 3 months, loads of attachments, process all orders, returns and customer enquiries etc through it.
We have several different departments for finance and whathaveyou, all our faxes are now converted to PDF, forwarded via email to the ticket system and are stored there.. this means loads of tickets with PDF attachments.. and yes, it is fine with it.
Only major concern is the volume of concurrent users causing slight delays, for instance, if you have 20+ staff connecting attempting to "claim" tickets, there can be a few contention delays. I don't think you will hit that.