Steve prolly has the best experience for comparison between v8 bushes and poly bushes.
The only thing I have to compare to is the nearly non-existent stock bushes and then installing poly bushes. Road noise went up? I can't say that it did so in any noticeable form for me. Then again, the old ones were nearly non-existent like I said earlier. The steering and suspension tightened up an incalculable amount. Again, a product of going from nothing to something.
From driving my car daily, I'll say that the road noise is not a problem. The exhaust note and tappet noise is much more prominent (with the Snug Top fitted) than anything else. Tagging "cat's eyes"/road reflectors gives a solid (but not jarring) feel with just enough noise to let you know you ran one over. Railroad tracks... well, that depends on the crossing mostly, but comparing to other cars my lowered suspension + poly bushes fares better than other modified cars I've ridden in, but it is worse than most stock suspension cars; obviously.
I've slated more work for myself this summer on the front end of my car, but none of the work is related to the bushes.