XTOL is very different than Rodinal - XTOL is based on a version of Vitamin C and contains some sulfites and phenidone. It offers crisp grain and full film speed and works well for pushing. Its shelf life is not as good and it offers less accutance than Rodinal. Rodinal also offers some highlight clamping that XTOL will not do. For an improved replacement for Rodinal try Pyrocat HD - It will cost you a stop, but will give you finer grain than Rodinal with many of the other simular benefits of Rodinal. 510 Pyro is probably closest to Rodinal performance and convenience. XTOL will cost you a small amount of accutance but overall will give you an extremely good image. For small formats, push processing or great enlarging - use XTOL. For larger formats, high accutance, highlight clamping and smaller (relative) enlargements - use Pyrocat HD.