If I might add thoughts from a novice VSL user ...
This VSL performance was amazing. Reminds me of the 'orchestral interlude' in 'Das Rheingold' which I think was also all tubas. Loved the crescendo towards the end ...astoundingly crisp.
I also like the fact that you have an actual theme (a very nice one!) at the core of this piece. This seems to be a rarity these days.
I did feel that the percussion (taikos?) was not necessary, but just my opinion...I guess you wanted to give the piece a film scorish feeling.
Would be great to hear a longer version that develops this theme, much like John Williams does in many of his scores.
Best
Anand