Ask HN: What do you think of Leanpub, Softcover, etc?

I'm working on a short technical book at the moment and I'm having a hard time picking the perfect approach to take.

Leanpub is one of the easiest to get started with.

Softcover provides a better interface for readers (and a lot of nifty features specifically for technical books).

But I'm also half-tempted to just go solo, publish the thing online for free and sell access to the PDF/screencasts via Gumroad.

Would love to hear people's opinions about the best way to go both in terms of the best way of writing, the best experience for readers, and also financial results — does being on Leanpub actually put you in front of a sizeable, willing-to-buy audience? Or do you still need to still give your book that initial marketing push?

Thanks.

:)