Like the other posters, I have not heard the tc 50`s, so take this FWIW. But I have heard other Piega models (and own the C-10ltd) and find them honest to the source material and quite captivating. I've owned large ProAc, Genesis, Dunlavy, Talon and Selah line arrays and the Piegas are, overall, the best of the bunch, to my ears. Soundstaging and layering of instruments is excellent and realistic and really draws you in to the performance.
I suppose one man's 'bright' is another's 'great inner detail.' They are more relaxed sounding than my Piegas. In my room (measured with Tact equipment) the C-10s don't sound bright and don't measure bright either -- they show a very gentle rolling off in the highs from 2k on, with a 3dB dip centered around 3.5k -- more neutral than any other speakers I've measured here.
IMO, the Piegas combine electrostatic-like detail and resolution with great musicality. And yes, they sound fast. My only complaint with mine is a lack of bass power (compared to say, the eight servo-controlled Genesis woofers I used to have). And I think the sensitivity ratings can be slightly misleading, as they require more power than one might expect to open up.
To respond to Spudco's remarks: While I realize people have a right to change their minds, it's interesting to read your prior posts on the Piegas. You say, "They are absolutely astounding... I can't even listen critically to my second system any longer (dunlavy V speakers)" and "These are so good, I'm even listening to some classical just to here the strings!" Obviously, you later changed your mind, but your characterizations sound like a nasty divorce.
Good luck with your speakers, lofimike. I hope you like them. You may have to change your moniker to 'hifimike.'