Brax and Helix come from the same manufacturer i.e. Audiotec Fischer, Germany.
Helix is the younger brother of Brax.
Brax is said to be one of the best amplifiers available as far as car audio is concerned. Hand made in Germanry, the brand is quite under-rated but are proven performers.
Here is a small write up about the extreme reliability of the amplifiers Brax X2400
I'd go with Brax of these two options, based on what I've heard about them. I've heard several cars with Brax amplifiers, but never one with Tru though. I think the MX4 must be VERY good, but be aware of serious Ampere consumption. The amp Doctor in the UK (Gordon, who founded Genesis) is another option.
He's able to custom build an amplifier for you. http://www.amp-doctor.co.uk/
I ordered a one-off 5-channel (4x108W+1x390W@4ohm) from him and it's fabulous. Better than the original S3 Genesis amplifiers, and the control and dynamics on the sub is just great.