do these pkgs maintain upgrade path from 2.7.x series installs via rpm ?
I don't know. I didn't use the phpmyadmin rpm from dev.centos.org, and I didn't check if the config.inc.php file from my old 2.6 or 2.7 install worked on 2.8, but I assume it would. It looks like both rpms will create a new config.inc.php file though when installed. I used the one from Remi Collet, but ended up changing the authorization method and protecting the directory with mod_auth_external. I'm happy to see someone pushing it in Fedora Extras though - looks like that was just posted today.
I took a look at Remi Collet's package. He's got some interesting scripts in the spec file. They attempt to set up the pma_* db and tables for you in mysql. I'm not sure I like the idea of an rpm install/upgrade operating directly on a (production) database. It might very well be harmless, but it just doesn't give me warm fuzzy feelings.
-- Any sufficiently advanced technology is indistinguishable from magic. -Arthur C. Clarke