JMLab Electra 906 / CC900 vs. new Focal Be's

I have a home theatre comprised of 4 x Focal/JMlab Electra 906's and an Electra CC900,
and I am looking to upgrade to Focal's latest offerings.

I am thinking about adding an SW 1008 Be subwoofer, then progressively replacing
my old 900-series Electra's with a CC 1008 Be center, some 1028 or 1038 Be's as
front speakers, and using my existing 4 x Electra 906's for sides and rears.

Has anyone any listening experience in comparing the old 906's (non-Be)
to the new Be series?

While there's no doubt in mind my mind that the new Be's will be vastly better,
my concern is that if I use the 906's as surrounds, they will sound too tonally different
from the new front/center speakers, and I will lose the uniformity that I currently have
(forcing me to upgrade to new Be surround speakers, which will be a pretty
expensive exercise!)

Thanks in advance for any suggestions or feedback - we have no dealers nearby with
a Focal surround setup, hence my reaching out here.
I'm using Profile 908s as surrounds with Diva Utopia Be's and the CC 1008 Be. They have worked hard to "voice" their lines as close as possible so that you can mix and match. I don't notice a difference, especially since the surround channels are not used as heavily in HT as the main and center. Also, they are behind as opposed to in front of you, so it would be difficult to hear a huge difference anyways.

I don't think it would be a problem to use the Electra 906s as surrounds for the Electra Be's. Good luck.