I think the bigger issue, besides pricing, is content lock-in, as you note. I've seen some other systems (not Baker, I'll check that out) that offer "free" app wrappers for magazine style content but tightly control the creation process as a lock in mechanism (and I'm not even referring to Apple here).
Curious: are you actually publishing to newsstand or standard apps? I'm wondering what the barrier to entry to the newsstand is in terms of approval vs. apps. At least with ebooks, it gets weird quickly on Apple's end (long long approval times for independent publishers unless you go through an "approved" broker, etc.).
We publish a standard app at the moment, because Baker did not support Newsstand until a short time ago. We will be updating in the next week or so.
DPS pricing is still bad. Single edition only gets you one issue. One freaking issue! You need to upgrade to professional ($495 per month!) or above to publish multiple issues, and then pay $.30 every time someone downloads one of your issues. Compare that to setting up Baker (free) and setting up Amazon S3 free account (15GB data out per month) and DPS looks like a total scam.