Basically, the Altigen is a PC. How many 10 year PC's do you have still working? You will have to change hardware out every 3 years or so especially HDs and Power Supplies.
The IPK, and all traditional phone systems, are all hardware dependant, but that hardware should last a real long time. I have many system in the field for 15-20 years.
Think of it like this. How often do you have to reboot your PC? Now how often do you have to reboot your key system. Why would you trust your business to a PC when for the same or less money you can get tried and true technology. Unless you have a real compelling reason for going PC based, stick with what you know will work for a long time.
Andy
http://www.teleco4.com