Slightly different from your normal Nikon/Canon argument. (I hope this is the right place to put this topic and sorry for the long winded story)

I currently primarily use a Canon EOS400d with the canon 50mm f1.8 prime lens. I've also got a Tamron 11-18 wide angle. And two kit lenses 18-55 and 70-200 which I haven't really used either since I purchased the 50mm. I also use an old Nikon f4 with an 80-200 f4.5 and an even older Pentax s1a.

I'm very much an amateur and don't want to destroy my hobby by trying to make a business out of it. I shoot a pretty varied mix of family portrait stuff of mine and my friends young family's, slow speed 4x4 events, cycling events, and general street art and landscape stuff. I was about to buy a couple of accessories for the Canon (battery grip and flash) and next Xmas was planning on treating myself and buying a nice lens... most likely the 24-70 f2.8L (I slightly understand the cropping element and from my research a lens in that range will be close to what I want)

Recently a mate planted a seed in my head that I should get rid of the Canon, and purchase and equivalent Nikon... Which is ~ $300-$500 from my diggings and all going well I should be able to sell my Canon for a similar if not slightly less price. I'm not attached to any brand, Nikon if anything feels slightly sturdier to me which I like but that's it. Ergonomics of the two I have no preference. I'm not likely to buy a high end body any time in the for-see able future. But would like to make my decision soon before I end up with too many brand specific accessories.

So is it worth the effort of selling and buying new gear for the ability being able to share the lenses between my film and dSLR's? The more I stew on it, the more I think it probably is. What are other peoples thoughts on this?