The main issue in this comparison question is so few people have played on, or own, Rasson tables, whereas there are a lot of people who have played on, or own, Diamond tables for over a decade now. With the Diamond you know exactly what you are getting, the pros and cons are well established as well as it's bona fides in professional tournament conditions.
The few professional tournaments that have used Rasson tables are being sponsored to do so. All the tables used appear to have been setup differently for each one, making comparison hard to make. Several have had obvious issues.
I did play briefly on a Rasson Victory II at
Billiards and Darts Direct who sell them here in southern California. It felt more similar to a Diamond than a Brunswick Gold Crown due to how the pockets were cut. Unfortunately like a Gold Crown they also do not appear to be able to make the corner castings line up accurately enough to satisfy my OCD brain. I quite like the surface texture the rails have, which has wood grain you can feel unlike the Dymalux/Dymondwood Diamond rails which are smooth. There is some debate on the stability of the aluminium frame in environments with large swings of temperature and/or humidity, and again their lack of a track record makes it hard to know how much of an issue this will or won't be.
The dealer told me it takes them 12 hours to assemble the Victory II from scratch given the complexity of the metal frame. To be fair it can take this long to assemble a Diamond Pro too, although of course a Pro-Am with 1-piece slate can be setup much faster. The price they quoted me for a new one was about 20% more expensive than a brand new Diamond Pro or Pro Am which surprised me given they are trying to break into the market.
Therefore IMHO, unless there is total lack of availability of Diamond tables in your area, or Rasson greatly lower their prices, or you just really prefer the ascetics of the Rasson, I see no reason to get the Rasson over a Diamond at present.