Greetings fellow RHCE-ian :-)!!!
Getting certified to stand out from the crowd does have it's benefits. As far as my knowledge goes and like you said, RHCA is definitely a level higher than RHCE. Whether it being the highest, I'm not very sure.
But I'd safely assume it to be the highest for now, i.e. if RH has not diversified it's certification stream into security related and administration, like some are doing these days.
Didn't you run a check on redhat.com? That'd be the first place to look for.