Hi sbdiver,
Welcome to the Mattress Forum! 
Tuft & Needle will request you to donate your mattress to a local charity as part of their trial policy of the product doesn’t work out well for you, and once they have a copy of your donation receipt they will issue you a refund.
Regarding Muse, it has been mentioned a few times here on the forum. You can click on this link for posts on the site mentioning them.
As for “reviews”, while other people’s comments about the knowledge and service of a particular business can certainly be very helpful … I would always keep in mind that you are the only one that can feel what you feel on a mattress and I would be cautious about using anyone else’s suggestions, experiences or reviews on a specific mattress (either positive or negative) or review sites in general as a reliable source of information or guidance about how you will feel on the same mattress or how suitable or how durable a mattress may be for you. In many if not most cases they can be more misleading than helpful because a mattress that would be a perfect choice for one person or even a larger group of people in terms of comfort, firmness, and PPP (Posture and alignment, Pressure relief, and your own Personal preferences) may be completely unsuitable for someone else to sleep on (even if they are in a similar weight range). In other words … reviews or other people’s experiences in general won’t tell you much if anything about the suitability, quality, durability, or “value” of a mattress for any particular person (see post #13 here).
Phoenix