the 2005 normal rotor is an analog rotor , a 2005 digital is digital , it's that simple..
the Hpi rotor is very good , I like the MHR rotorkit more cause it is easyer in use , plug and play and very good performance. but it is more expensive then a analog HPI , the digital HPI is very nice and works fine but you'll have to really know what you do if you change ignition curves..