Hi Cristoo,
I own both and agree with your initial thoughts. I would buy both again, just received my 2nd RB6U today and a 2nd Mantis is on the shopping list. Don´t assume you won´t want a bigger system, I made that mistake at the beginning, but see where that got me :).
Adding to your findings:
Rackbrute:
- Got my 2nd RB before the 2nd Mantis. I´m building a small portable system first, studio extension comes later. As that unit has mostly black faceplate modules, the RB looks much better. That does of course not impact how modules sound. It´s just a bit of eye candy on top of the important things.
- Metal case, more solid, but also much heavier.
- There is an Arturia softshell Travelbag that looks solid, has paddings etc. Check MW for reviews on the Mantis bag.
- Combine 2 RBs with a flexible angle between them, this also serves as a carrying handle. Much better suited for medium live systems if you perform or move between home studio and friend´s places.
- Said Combo gives you a gap between upper and lower, good if you can use that, bad if you don´t. I feed longer cables there to get them out of the way.
- Smaller PSU in an odd width (5hp). If you run out of power and can´t move modules between cases, there are option like StrongPWR (4hp). They add to the overall cost of course. I hit the limit, but was able to move things. Use modulargrid to estimate power consumption.
- Placement of PSU module is a bit limited, as the default cable to the distribution board is quite short. It has a standard connector though, an extension is possible, but may need a custom approach. I´m also concerned about interference, but that´s theoretical for now.
- No decksaver option, so dust protection must be improvised (or fold the upper above the lower in my case).
- Without the bracket, a single RB works great on desktop, but is still a bit higher than the Mantis. If you work in studio only and place it directly on the desktop, Mantis is preferred.
Mantis:
- Much more elegant formfactor, the curved design is just very, very nice. Does not alter sound, but makes the modular just so much sexier to look at. You may disagree. Looks great with silver faceplates.
- Plastic. Sturdy plastic, but plastic. Color may change over a long time, think old computers, but then again a paintjob can easily be done. I actually think about spraying mine in screaming orange, but that´s a different story.
- Fixed angle for the brackets. May or may not be a good thing, I can´t tell yet. The slight angle of the upper row is a godsend already, much appreciated, so I assume TTA did their homework. Brackets will give more stability, but I think I´ll probably skip them and build something with a custom angle.
- Dual Mantis is definitely immobile (when using brackets). Gives you gapless connection, pros and cons see above.
- Depending on your needs, price/performance ratio is on par with the RB, it´s just the question if you want to get mobility features vs power and space. Your usecase will decide that.
- Much beefier PSU, does not waste hp, more connectors from the board.
So in all honesty, it´s a draw in most cases unless your application would make one or the other difference a deciding factor.
Timeline of my shopping: RB #1, Mantis #2, RB #2. Next stop Mantis #2. So from my perspective, both are good value and I haven´t found any showstoppers.