Career wise, both KVH and Thomas are about 36% from 3 point range, so it's a wash there. Thomas is a much better defensive player, especially on the perimeter. He is a better shot blocker, although neither one is exactly like Bill Russell (or Manute Bol, for that matter
). KVH is a better rebounder.
Thomas should be able to run with Marbury better than KVH ever could hope to. If the fact that he's playing near his hometown motivates him, this could be a hugh deal for the Knicks.
Time will tell.