The problem is that 'experimental' doesn't really mean anything. When your average Bowie fan hears the word 'experimental', he probably thinks of the Bowie albums labeled experimental, namely Low, "Heroes", Lodger, Buddha Of Suburbia and Outside, all of which inhabit something of a similar ground. By this definition 'experimental' is just another musical style like glam or soul.
Exactly its a very loose term. even Aladdin Sane and Diamond Dogs could be considered exprimental. Its a over-used term in the Bowie vocabulary.
BTW Bowie wouldnt have been the first to collaberate with the Polyphonics. Death in Vegas (with Liam Gallaghar) have and even Peter Gabriel.