Work through the steps of each way and evaluate them to suit your needs........And at times your needs may vary.
Balanced........ Mic into the SD302 (with great preamps) do the mixing and level controlling then drop it to mic level to go into the crappy H4n mic preamps so you can record the signal.
Unbalanced........ Mic into the SD302 (with great preamps) do the mixing and level controlling then sending it to the H4n at line level (yes unbalanced) but you will bypass the crappy mic preamps of the H4n.
IMHO if the recorder is VERY close to your mixer (in the same bag) then use line level and unbalanced inputs....... If the recorder is away from the mixer then use the advantage of balanced cabling, use the correct signal levels to get the best signal /noise possible.
Unfortunately the H4n's line input are (consumer level) -10dB and unbalanced via it's 1/4" inputs of the 1/4"/XLR combo input connectors. The 302's XLR output is normally pro level balanced and would not work well. It can however be attenuated to mic level via the 302's software menu. For short cable runs, the 302's 'Tape out' would work well with a TA3 to 1/4" adapter cable.
AFAIK, there is no way to totally bypass the H4n's preamps regardless of what input is used.
I do not comprehend what is the advantage of using UNbalanced anywhere if one has the choice?
And if one doesn't have the choice, then the question evaporates.