I agree with Danny. The 4050 will give you more versatility - especially on instruments. Great on female vocals, too. The 4050 is a bright, neutral mic.
The C3 is a colored, hyped mic that works well on vocals, amps and even kick drum.
I'd recommend just getting the C1 is you're looking for a vocal-only mic.
But for miking "non-electric" instruments, forget the C series all together - except for the SP T3. They blow on acoustic guitar. Actually, the SP B1 is excellent on acoustic instruments.
Between the two, I'd chose the 4050.
There are very few mics that actually pull off doing both vocals and instruments well.
I'd also look at the ADK TL - which is a neutral mic with 4 patterns. Very versatile. Also, the Red5 Audio RV8 for cardioid or the RV10 for multi-pattern.
I personally would chose the ADK TL over the 4050, because all the AT mics have this inherent slight grainy sound - which can be cool, but you should know that going in. The ADK TL has a smoother sound.
To answer your Q: between a C3 and a 4050 for your applications, the 4050 gets my vote - easily.
My 2¢.
Dan Richards
The Listening Sessions
The Project Studio Handbook