Rhino sourced the episodes from pre-broadcast prints with unfinished animation and errors. They also had a new 5.1 soundtrack made with terrible sound effects. I believe the original audio was also included on the Rhino DVDs, but not on every episode. The Shout Factory DVDs is also sourced from the same master, but with inserts from the broadcast tape and the original mono audio is present on every episode.
Here's a video showing the difference between the pre-broadcast and broadcast version of the episode S.O.S. Dinobots:
I was perfectly happy with the UK Metrodome DVDs based off the Rhino source - The increased clarity of the picture more than makes up for any of the errors imo (and I didn't notice the 5.1 sound since I only have stereo speakers). Transformers was always a QUALITY show anyway. I'd say for £12.85 (which is about what I paid for the singles in HMV - £2.99 each for four or £29.99 for the box. Hmm. Tough decision) it's fine. I probably wouldn't have paid £30 though, you can import the fixed US set for about that.