Hey, thought I'd chime in with some second judge feedback.
I've seen your form letter in the inbox and while I disagree with the minimal source connection - in fact, the bass and synth strings carry it all the way through - I do however understand your critique for the bass connection getting pushed under. Perhaps doubling the bass riff (but not the repeated non-source notes) onto another instrument, preferably an octave higher, can give it another boost. The arrangement structure itself is solid though, going through one variation of the theme with textural variations between similar parts - even with a fun solo for the last minute. For what it's worth, the transformations are reasonable, though as mentioned, layering your parts can help bring out the source more.
Addressing the other production crits - sample quality here spawns more from your individual instruments sounding like they've only got one VST per part, meaning leaving an exposed impression on the mastering. It is possible to import non-Propellerhead VSTs into Reason whether you decide to invest in some or find some freebies, and it's not impossible to get a mixpost done with just the defaults (but it takes a lot more work). Whatever direction you go in, if the sample itself doesn't have more than one layer, it's best to layer it with some other sounds. Like, if you want a bass to have more sub-bass, find something that has a square or triangle tone and cut all frequencies above the highest note your bass ever plays. If you want more air in a synth, use a harsher saw tone and cut all frequencies from the lowest note the synth plays. Here is a chart with every frequency on all notes on an 88 key piano - that should help with figuring out where to make cuts.
Another way to give your instruments life is to take a look at envelopes. Bear with me, as it's been years since I've last used Reason for anything - but I believe you can set envelopes for certain parameters within a VST, and not just volume and panning. You could use it to manipulate cutoff, resonance, modulation, the wet mix of an external effect, or even bending the pitch if you want to get that creative. It would make your synth solo sound more like a lively synth rather than something that gets tapped multiple times a second.
And let's go back to the last statement you received - the "needless sizzle", or the mastering being way too bright. If you air the track in a music player that has a visualizer, you can see that the higher frequencies are pushing as hard as the bass and low-mids, which isn't normal. Higher-pitched instruments are there to add some sheen, but definitely not too much. Assuming Reason comes with a decent EQ plugin, it's best to make mid-high EQ cuts from instruments that don't benefit from it (bass, lower synths, strings) and let those higher-pitched instruments just shimmer. If the problem still persists, consider bringing down the volume for your hi-hat, cymbals, bells and rhythm parts in that range.
Anyway, I hope these critiques can help you out. It's frustrating to push yourself so hard and get a DR, but don't lose heart over it. The fact here is that you're willing to improve yourself, and whether you decide to refine this track or work on another, it'll be cool to hear from you in the inbox again. Keep at it x)