What I've heard so far as I'm darned interested in both models:

Watertechcorp.com is the company of the son of the founder of the maker of all the Aquabot robotic cleaners. They also make the PoolBuster. They make the Blue Diamond (regular and remote control) and a commercial version of the Blue Diamond. In 2006 they came up with the Blue Pearl, which is a slower version of the Blue Diamond with a 3 hour cleaning time and lacks a sensor or two as well. How this impacts it's effectiveness, I don't know.

Going to the website that you are requested to send emails to about service leads you to www.aquatron.us and that's the "high class" side of the famous Aquabot line. It features the Aquabot Bravo and Aquabot Viva. Looking at the pictures, these are probably identical to the Blue Diamond and Blue Pearl. The giveaway in my eyes is the single or double PVA rollers/brushes that ONLY the Blue Diamond/Blue Pearl and Aquabot Bravo/Viva feature.

So in my investigation:

Blue Diamond = Aquabot Bravo
Blue Diamond Remote Control = Aquabot Viva
Blue Pearl = Since neither the regular or premium Aquabot lines have a cleaner that matches the Blue Pearl's specs, I suspect it's actually a new product with no Aquabot cousin.

The more I research, the more confused I become with all this damn co-branding and relabeling. In the end though, I think I'm going to get a regular Blue Diamond as it's cheaper than the other models and with the Dolphin horror stories, it's worth a shot.

Hope this helps