Just some info for anyone else out there going through a similar decision as myself. I received some correspondence from Lonnie at Emotiva that might be of value to some of you. In general, Lonnie thought that the IPS-1 would be my best choice out of the Emotiva amps, considering that I am very happy with the RPA-1 and am not too excited about paying the price increase on the MPS-1.
From Lonnie: "The IPS would more than likely be your best option here. It uses exactly the same technology and design as the RPA, just with a little lower power. It also has the same gain structure, so they would match up perfectly and would give you the ability to drive zone 2 speakers or move into a 7.1 system at a later time."
In addition, I asked about the upcoming XPA-5:
Q: "Do you think that the IPS-1 will outclass the new XPA-5 in terms of performance?"
Answer from Lonnie: "The IPS will definitely outclass the XPA-5. The IPS is a dual tracking class H which easily out performs the Class A/B."
Adam