4 ohm 2ohm SQ question

In laymen's terms, all amplifiers will run hotter at a 2-ohm load than they will at a 4-ohm load, since the lower the load on the output the higher the current draw through the amp.  This shortens the the amplifier's life expectency and makes them more prone to failure from over-heating.  It forces the output transisters to run closer to their thermal maximums.  Almost all amps will be noisier and distort more when running hotter and closer to their maximum amperage ratings, resulting in a perceived loss of SQ.  Some high-quality amps can handle a low ohm load in the mid to high frequency bands without noticable changes in SQ, but not many.  For subs, the loss of SQ in the signal is not nearly so noticable as it is in the higher frequencies.  You can generally achieve acceptable SQ at 2-ohms with sub amps running below 100 Hz.  But in higher frequencies the distortion and loss of S/N ratio is more noticable and can make a system sound very bad very quickly. 

That being said, there are also some mid-to-low end amps designed for a 2-ohm load now appearing, especially in OEM car audio systems.  Since a 2-ohm speaker will play louder (all other things being equal) than a 4-ohm speaker, it allows car manufacturers to make their stock systems seem "better" since they will get louder.  But they also tend to distory much sooner and the factory amps will not last as long as the same gear would running at 4-ohms.

My curiosity is directed toward an Arc Audio 2100 cxl.  I was considering running my 2 sets of components off it. (6.5" alpine type-r)  What do you think?

Which is exactly what I would recommend as well.