Paul Simon may be one the best examples of longevity and success of a mainstream artist, despite or possibly thanks to, his many musical experiments and forays into uncharted territories.
As much as I love Neil, I'm not sure that it's a fair comparison. Neil's #1 for me, but unfortunately he's never achieved the same level of Super-stardom as let's say Paul Simon, Peter Gabriel or Sting (I'm not saying he doesn't deserve it, it just hasn't happened yet). If we were to measure peaks based on album sales, they all hit their peak 30 years ago.
Another huge difference is the fact that Neil hasn't really strayed too far from his main path. Looking through his musical career, there's rally nothing mind-blowing or wildly contrasting from the his early days with Split Enz all the way to Dizzy Heights.
Of course he's tried different formulas, outlets and avenues along the way; some more successful or commercially appealing to the masses than others. But as much as I love everything he's done (except for most of the Pajama Party), I think maybe Neil's one failure has been the rigidness of his songwriting/arrangements. Like many other musical geniuses, he is his own worst enemy, and as much as he's tried to do different things, he's too entrenched in his own style (which for us fans has resulted in a n extremely rewarding 40 years of music). The problem is, Neil knows this and is constantly trying to 'break the chains' by surrounding himself with people like Youth, Michael Leunig, Radiohead, Sebastian Steinberg, Wilco, Jim Scott, Dave Fridmann, Tim, Liam, Sharon and others...but he just can't get out of the 'Neil Finn' cage. I'm OK with Neil being Neil, and to me it never sounds better than when he's surrounded by his band, Crowded House.
Personally I've been a little turned off when Neil has attempted to be experimental, it just comes across like he's trying too hard to sound like someone else (whether it's tinkering around with effects or over producing stuff) and in the end his songs don't really benefit from this process; a good example of this are the songs on Pajama Party, some of the songs on Intriguer, his contributions to The Sun Came Out and Lights of New York and Dive-bomber from Dizzy Heights.