I did a power cord upgrade on a Challenger many years go [like early 1990s], and have not seen another Hilgen amp since. Nice amp, simple design, one spring reverb [it still gets 'lush', but not 'deep'] and a tremolo circuit, IIRC.
So I can't tell you how it compares to the Champion model, but if the amp is working [and the power cord has been upgraded] it was a nice little combo. The Champion, I believe, was a piggyback head/cab, yes? Never saw one in person, just pics [Hilgens show up on Reverb sporadically; they have been out of production for what, maybe 60 years?]