Both Blaze and Marine are very fun to play as! Not perfect, by all means, but the main problem I have is a more personal gripe rather than a problem with the mod itself.
POSITIVES
+ Both Blaze and Marine have abilities that can be used by both beginners and experts. Both characters are really good at speedrunning nonetheless!
NOTICES
/ It's rather easy to softlock yourself out of getting a Sol Emerald. Pressing "Retry" doesn't seem to reset it... I would've preferred replacing the regular Chaos Emeralds with Sol Emeralds, but I am not sure how feasible that is.
/ During a run with Marine, after dying a few times I beat the Egg Coliseum without getting hit, at the game hard crashed trying to give me a Sol Emerald... Keep this in mind when playing as them.
/ The Sol Emeralds only seem to unlock Burning Blaze (And maybe Super Marine?), they are NOT required to get the best ending, only the Chaos Emeralds are!
/ Although I obviously haven't collected all 7 Sol Emeralds, it seems that since you get a specific color per boss, by the time you get all of them you would be fighting the final boss, meaning you wouldn't be able to use them all the same... But I cannot prove this, hence why its in "Notices" not "Negatives
Bottom line, both characters are very fun to play as, I just have a few nitpick with them.