Hi Matteo,
Love this tune! I mostly agree with Sean's comments. (I didn't listen as carefully to the placement of the line relative to the backing on the head, though, so although he's probably right I can't comment on it one way or the other.) The kind of tone and note production that he praises are
areas I find particularly difficult, and you indeed do them well. I tend to have problems with "blatting out" especially in the low register. Since I play a YTS-23, your post may inspire me to try a regular tonedge instead of my current "New Vintage"... you are playing a regular one, right? I'm assuming 25 is the updated model corresponding to the 23?
I only had one other observation on your take beyond Sean's, which is that in the last note of the first (or maybe it's the second, depending how you count...anyway, the 8th note of the tune) phrase (and analogous phrases later one) of the head, I think it would sound better if the accenting were reversed, i.e. placed on the last note of the phrase instead of the next-to-last. That is syncopated, but sounds better to me. Funkier. If you can't find the place I"ll hunt down a lead sheet and pinpoint it. It's just my taste, though, you might prefer the other way of course... Other than that I liked the phrasing in the head pretty well.
One other comment for improvising is that even over a modal tune, playing some beboppish phrases, like ii V7 's either in the key you're in or anticipating a change in chord, can sound very cool. It can add some harmonic movement and interest. Not that I have mastered this, I am definitely still a learner, but I can hear it in others' playing sometimes, including guys like Wayne Shorter who play a lot of these modal tunes. Ditto George Coleman, e.g. on Herbie Hancock's Maiden Voyage. Stanley Turrentine and Gene Ammons also do it, usually in a more soul-jazz or funky blues context but again, often over one-chord or few-chord jams. But I don't know if you're into ii V7's yet. If you are, I would say mess around with them on this tune and see if you can get something to fit.
So I agree, keep it up, you've got a great sound, some good ideas, definitely a foundation worth developing further.
Howard