Marty,
I was in a situation similar to yours a few years ago. I had been using an old (but loved and will never sell) pair of Polk RTA-11t floor standers along with a Definitive technology CLR1000b center channel speaker. I longed to upgrade to Aerial Acoustics but it was such an expensive upgrade. I decided to purchase a CC3b to replace the CLR100b. I soon sold the CC3b because I could not tell a huge amount of improvement.
However, I still wanted three identical (at least in manufacturer) speakers across my front soundstage. I next purchased (3) B&W Matrix 805 which gave me identical speakers across the front. This did provide seamless movement across the front LCR channels, but, even with my sub the dynamics were not what I had with the Polk/Definitive combo. Moving from floor standers to bookshelves proved to be a big mistake. The mismatch in manufacturers proved to be less important (to my ears) than having identical across the front. So, I sold the B&W's.
One day a single Aerial LR5 showed up on Audiogon. I knew the LR5 was identical to the CC5 in a vertical design. I also had been thinking of trying one because of the excellent reviews and recommendations. I decided to call Mike Kelly at Aerial for his advice for an upgrade path.
His statement was that not only was the LR5 identical in design to the CC5, but, it actually performs BETTER than the CC5 for center channel because of it having its drivers arranged vertically instead of the market driven horizontal array.
He then said that for pure HT listening 80% of a typical movie's soundtrack is mixed to the center channel. The center is the most important channel in a home theater. He also added that the LR5 (or CC5) is such an excellent performing center channel speaker that it would make any lesser set of mains sound even better in a home theater set-up.
I listened to his advice and bought the LR5; hoping his comments were accurate. i've got to tell you, he was absolutely correct. For the first time I could tell an ENORMOUS (bigger than huge) improvement in the sound of my front soundstage when I added the LR5 as center to my Polks. I'm not good at describing the details but I will try. The bass was deeper and tighter, there was more fullness to the sound, there seemed to be an added dimension or depth to the sound. It was amazing. I sold my CLR1000b and kept the Aerial. This but me on the path to upgrading my mains to LR5's to match.
I just last week purchased a Proceed HPA3 to power my fronts. This is replacing my Parasound HCA1206. Knowing how the Aerials love power, I knew an amplifier upgrade was needed. I feel the upgrade to the proceed is again a gamble, but I want to see if I can tell a difference, at my listening levels, with the additional (actually double) power provided over the Parasound.
I say start with the CC5, or LR5, as center and build around it. I don't feel you will get the ultimate performance with the 6's as opposed to a larger Aerial, but, it will sound excellent until you can afford an upgrade.
Just my opinion.
David