Seems solid
There are some tweaks I think you should look into. Be on the look out for balance and blend. When arranging classical pieces it's important to remember balance, think of it like a balancing a scale or playing Jenga, you don't want a song to be too top heave (meaning higher pitched voices) or too many low voices either, you have to find a common balance in between. Another thing is blending. You have to take into consideration what instrument voices can do and what they stand for and try to find a way to blend them with other instruments. Example, flute and trumpet, they both are soprano register instruments but a trumpet is naturally stronger than a flute. Trumpets are usually used to carry the melody or theme because they can overpower most instruments, on the other hand a flute is mostly used for embellishments or counter melody. A lot of times when a flute has the melody all the other instruments usually back off in volume to accommodate the light sound of the flute.
Now with that being said. there's nothing wrong with your instrument choices. In fact, I think it's quite good. Some thing I want to point out though is that from 32 seconds in to 43 the reed sound seems a little over bearing. It sounds like you have two different voices playing the same note, maybe lower the volume on one of the voices or change the pitch of one of the notes to a different note and make it a harmony. Another thing that struck me is that at 1:04 a brass sound comes in (a trumpet I think) and kinda gets over powered by the choir, I don't know if you want it to be that way but to me it feels like the trumpet is caring a melody if it is you might want to push the choir back by lowing the volume on a them a little. Another thing is that if that is a trumpet, then it's going way too high right at the end. I think it would be cool to make it a trumpet fanfare right there at the end by adding a harmony to that line at 1:04. That's what I have to say. Sounds really good, good luck with you song and thanks for sharing.
Also,
what software do you use? if you haven't already done so you might want to look into using the Graphic Equilizer if your software has one. I also want to offer you my ear as a sounding board so please feel free to ask me any questions about the development of this song, I really want to see this be something really great.
later,
Jay
blackattackbitch 
