first off, this is sick!! i don't know if you'll even read this, and i can't pretend to know your end goal for this (whether you intend to submit it to ocr or not), but i'm going to leave a long non-mod review anyways because of how much i liked your arrangement, haha.
the bass/b3 writing during the turnaround at 1:03 is really slick and the whole chord progression sets up the solo section around 1:19 nicely. though the snare sample you're using isn't particularly strong, and is also more exposed since all you have essentially are the b3 comping chords and electric bass locking in with the groove.. i'd recommend maybe side sticking over snare for that specific section. it'd also help to reinforce the identity of the solo section as such.
i feel the drum writing in general could stand to use more variety.. especially alongside your harmonic/melodic writing, which is killer. simpler drums are fine for establishing the groove, but after the third or even second time through the vamp, the beat starts to lose momentum, and the listener, expecting development, loses his will to groove/live. maybe fill some of the gaps between hat hits with 16th note hat hits, irregularly, so your hat pattern gets the double benefit of sounding more syncopated and not like a two - four bar loop, and use some quick open-to-close hat hits for good measure! most of your fills last about two to three beats before the upcoming first bar of the repeated vamp and could be more developed; give your fills a space of the last measure or measure and a half before the vamp repeats! treat your fills (and more macroscopically, your percussion as a whole) the same way you'd treat the notes of a melody: carefully and deliberately. that way they will sound more intentional and less like an afterthought. ride-bell hits and flams over single snare hits are always stylish too, used sparingly of course. making the drums more exciting alone would introduce a lot of compositional energy into your arrangement.
the improv is stellar. i've looped your piano and e. piano solo probably ten times already. the few parts where you slug the rhythm during your piano solo, and the first time through the melody, are really tasteful and clear indications that one, you would be awesome to jam with, and two, you probably like a lot of the same music that i do! so i hope at least some of what i'm writing hits home.
this one is more of a personal preference. b3s ought to scream. where is the dirt, the crunch? i appreciate its mellower sound during the e. piano solo, but a more distorted sound could be contributing so much more energy to the previous section that builds up to it! the b3 sounds like you've slapped a lo-pass over it at around 2.2 khz, denying all frequencies above that the chance to see the light of day. tragic, i know. there's a disturbing lack of high frequencies in the mix balance. you have a lot of instruments already filling up the low to mid sections of your frequency spectrum (i count kick drum, bass, acoustic piano, e. piano, and currently the b3. the clavi sounds mid-hi to me), so lessening the chokehold on the b3 would also be a great way to restore balance to the force, and your mix!
with respect to other mixing considerations, your levels sound fine, nothing seems to need reverb, and the separate tracks all sit in their frequencies nicely. the last step towards a more believable, a.k.a. samples-masquerading-as-live-musicians mix, aside from acquiring more realistic samples and hand-tweaking note velocities, would arguably be panning to cleverly emulate the stereo image of a live performance as live musicians occupy different areas of the stage/jam floor. also, is it just me, or are the hands of the supposed clavi player panned hard left and right, respectively?
i'm guessing you haven't mastered this yet, because the overall level of the track is on the lower side. some slight mastering compression would go a long way in bonding the separate tracks. the instruments on the low end of the frequency spectrum (your kick drum and bass) could stand to be brought up with respect to the harmonic instruments. you might as well fix this in the mixing phase, or you can slightly compress the master track from around the 55 hz to 200 hz range with a multiband compressor and add some makeup gain, which will give your mix the buff "level 10 kick and bass tightness". non-dispellable. no expiration timer. the drums lack a bit of presence compared to the other instruments as well, most obviously at around 1:00. i'm bringing it up here because i'm not sure if they'll be better or worse off after the compression/limiting mastering phase, but there's a good chance that they'll benefit from a two to three db boost on its volume fader and some light compression. you definitely don't want to kill that live sound, so a 2:1 ratio and a threshold of around -15 to -18 db, with a quicker attack and medium release, should give them more punch while avoiding making them sound overly produced.
the mix clocks in at just over two minutes; long enough to establish separate sections, and short enough to make me want to repeatedly hit the replay button.
really hope you take another look at this man!
edit: for preserving star wars canon