Elegia in C Minor for String Quintet

Hello everyone, 

I recently updated a little draft of music for string quintet on the incomplete works forum and I just developed it into a full piece.
After some thought, the section felt somehow like a developed theme, so I composed a main theme by using some of the musical features found in that draft I composed.
I also changed instrumentation, having two cellos instead of a double bass (as in the initial draft) and increased the tempo from 60bpm to 70bpm.
However, I do not use the second cello so often and it just doubles the other one at the octave most times so I am wondering whether I should just turn it into a quartet instead.

The piece is an elegy and has the following sections:
[m.1~m.9] Introduction -- The introduction was composed by making use of the most important harmonies of the piece: Cmaj, Cminor, Dbmaj and Gmaj.
[m.10 ~ m.25] Main theme -- Main theme in C minor. It works as a period but, in this case, both statements end in a half cadence (the second has a stronger modulation to G)
[m.26 ~ m.40] Development section (original draft) -- Developmental section which starts with the main theme in Cmaj. This section is repeated once.
[m.41 ~ m.51] Restatement of main theme -- second part of the main theme repeated once, this time ending in a perfect cadence (with picardy third in last chord).  

I think the atmosphere fits the title of "elegy", but let me know what you think! 
Also, a distinctive feature retained from the draft is the use of pauses that resemble deep sighs (or holding ones breath). I took as much care as possible to make those moments sound natural but the midi sounds showed its limitation in those cases :S. 

I am thinking on updating it so both violins get to play the melody at some time, doing some voice exchange like that one I did in measures 14-15.
Is it standard practice to share melodic material between the two violins in order to create an echo effect and add variety for both performers, even if the melody could be written entirely for Violin I?

As always, every feedback is more than welcome and hope you enjoy it!