It's easy to focus on the negatives when you've had a bad experience, and Massdrop is not close to perfect. Their big positive: Massdrop are able push through Colevrak, Norde etc. they usually get enough sale for MOQ on extras like ergo, ortho, Cyrillic, Hiragana etc.
Red Samurai is a strong design and it stands out amongst a lot of 'me too' keysets, I'm sure it would sell very well via any of the bigger GB retailers known amongst the community here and on Reddit, but there are a lot of extra kits and Massdrop is the place where I'd have the highest confidence of getting them all made.