I debated over this myself haha. 
I have the new black glazed MC N/S tote, and was going to buy the dark brown MC E/W tote, but IMO, the dark brown is very close to black, and it's difficult to differentiate between them... plus, then I would have had two very similar looking bags for a lot of $$$$. Also, I perfer the N/S in black, and the E/W in dark brown. 
I recently purchased the dark brown GST, and it's just gorgeous, because the chocolate brown looks very rich and saturated in the caviar leather, and while I initially thought the GST was too "boxy," etc. after having tried various GST's on in the store, I really like the way it looks on. Hmm, I wouldn't necessarily place too much weight on cost (although, the GST is definitely priced more "reasonably"), but on which one you'd wear more! If it's the GST, then get that, but if you're set on the MC, then that's the best way to go. Good luck deciding... my vote goes to the GST, and I can't wait to see pictures either way!
I have the new black glazed MC N/S tote, and was going to buy the dark brown MC E/W tote, but IMO, the dark brown is very close to black, and it's difficult to differentiate between them... plus, then I would have had two very similar looking bags for a lot of $$$$. Also, I perfer the N/S in black, and the E/W in dark brown. I recently purchased the dark brown GST, and it's just gorgeous, because the chocolate brown looks very rich and saturated in the caviar leather, and while I initially thought the GST was too "boxy," etc. after having tried various GST's on in the store, I really like the way it looks on. Hmm, I wouldn't necessarily place too much weight on cost (although, the GST is definitely priced more "reasonably"), but on which one you'd wear more! If it's the GST, then get that, but if you're set on the MC, then that's the best way to go. Good luck deciding... my vote goes to the GST, and I can't wait to see pictures either way!
I've also seen the dark brown in both the E/W and Hobo styles, and the new chain is really pretty, because it's a shinier chain that really compliments the subtle sheen of glazed calfskin IMO. Hmm... I still think you should try on the GST and MC... or you could replace your old MC with the new one, and still buy the dark brown GST! 
Good luck!