I agree with Tom, you don't mention your music versus movie %? If you like cranking things up from time to time, I think the 60's will server you better. For HT watching in that room, I would consider the EP350, it is an awesome sub that will fill that room, the 175 may not move enough air.

To answer your question, I don't know anyone with downgradeitis.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85