i just started using your system and it's great for a small helpdesk. i don't understand how you are making money but it's really nice not to have any banners or ads in emails etc.
The only problem i have noticed is a lag of 10-15 minutes in sending notification emails.
Have you thought about adding some premium package with a monthly fee and invest these money into better servers, bandwith etc? I would be happy to pay the subscription to get rid of those email delays.