Likewise, I agree with the proposal. Personally, I've upgraded any RH7.1 -> 7.2 machines through to 7.3. That process itself is fairly painless and 7.3 & 9 are the most supported legacy distros.
As for RH8.. :) Why anyone would run it is beyond me and upgrading to RH9 is painless too (even remotely). :)
I've personally got a Redhat 7.1 box and a Redhat 8 box both of which I've considered upgrading, however I'm very skeptical about doing it for fear of it stuffing up. (these boxen are in production!) :)
How well does the upgrade happen? does it keep config files and so forth?