Excellent choice.

>> I didn't want to drop down to the 1pi or 2pi given that these use
>> the Motorola piezoelectric tweeter

Actually, the tweeter is excellent but the overall speaker design doesn't provide as much dynamic range or as deep bass as the larger speakers do.

>> Also, what are the sound differences between the Thermionic and
>> Theater systems?

They sound pretty similar, but the Thermionics can be used on tube amps while Theater Series three π speakers are not recommended with certain impedance-sensitive tube amps.