I love my 24mm f/1.4 II and it was definitely worth the upgrade over the mark I for me. But I don't recommend sacrificing your ultrawide range just to get the Mark II -- a lot of times 24 just isn't wide enough. So you should look for some way to afford both a 24mm and a 14mm from the start. My suggestion is to go for the inexpensive Samyang (AKA Rokinon) 14mm f/2.8.