Compared to what would be REALLY RIGHT in an advanced DSLR of 2012, the Nikon D4 & D800 come closest:All these points can be done in the 1D4 (except for #3 as there is no P mode)
1. EC correction available in M-mode with Auto-ISO ... YES
2. Minimum threshold for shutter time 1s to 1/4000 [not limited to 1/250s] ... YES
3. In modes A, P where cam determines shutter-speed, focal length is taken into account ... YES
4. this shutter speed can be further fine-tuned slower/faster by user ... YES
5. Auto-ISO in D800 [@ € 2800] not crippled, but exactly as in flagship-model D4 @ 6k ... YES
5D3 Auto ISO - which is main subject in this thread - sucks on all five points.
And 1D IV also falls way short ...
1. only available via twisted workaround in "faux M-mode" ... using Av and setting min and ma shutter speed to the same value.
3. focal-length-aware shutter-times in Av,P mode plus Auto-ISO not available in any current Canon EOS body
4. also not available in any current Canon EOS body
5. all Canon EOS below 1 series are artificially crippled in their Auto-ISO functionality for "marketing differtiation" reasons. Annoyingly so, even and especially where pure firmware items are concerned.
Compared to "2012 gold standard" [Nikon D800, D4] Auto-ISO functionality in all Canon EOS bodies is inferior ... big time in anything including 5D 2, considerably in 7D and 5D3, still quite a bit in 1D IV / 1D X.
If you don't need it or use it due to personal preferences and or shooting situations, fine. But there are many others, who would love to have and rightfully expect Canon to deliver more bang for the buck on this.