I am an amateur who plays at a reasonable level, but am by no means a professional. I wanted to purchase a good-quality all-rounder that suited my current ability, will still allowing me room to grow.
The Michael Rath R400 is a beautiful piece of equipment. It produces a full, vibrant sound, and supports a variety of different sounds and approaches. It is very supportive in the upper register, and avoids sounding tinny or hollow at pitches above C5. However, the response and sound can be a little so-so in the first 15-30 minutes of playing, which is something I'd read prior to purchasing, and so did not find surprising when it happened to me.
I like the deisgn - the instrument feels balanced in the hand, which is contrary to one of the reviews I had read prior to purchasing. I love the trigger design, and the support that is positioned near it. The tuning slide and the slide lock are the only mar on the design and quality - I personally dislike the locking mechanism. The tuning slide is prone to sticking, even after careful application of grease.
The instrument seems to be exceptional value for money, producing a quality of sound that I would only expect in instruments twice as expensive. Contrary to the description, the trombone comes with a mouth piece and gig bag. Both are fine, but are nothing to write home about.
9/10, would definitely recommend to any player from medium level onwards.