Can't say for sure but it's going through BETA testing now:
Pulse5.1 (out in a couple of weeks) has an update which will allow it to import Pulse Builder templates. So we're getting a lot closer!
Blocs app is an excellent app and integration. The main reason Pulse Builder exists is that because it is web browser based, it will allow Windows user to also integrate with Pulse site building - rather than just focusing on Mac apps. Blocs app can export standard HTML also but Pulse Bulider only Pulse compatible templates.
Re the price, with Builder and Ecommerce on the way, and form building already here, Pulse is now a platform so excellent value for the price. So you pay to get access to everything for helping you to make either 1 or 100 sites. So it's a set fee for any number of sites, depending on how much you want to use it.
If you are creating a single site for yourself and want to pay less, than Blocs is excellent.
If you want to create a single site for a client who wants to edit the site later - then the Pulse price is also excellent as you can then charge them appropriately for giving them this extra value add and make back this cost and profit on top.
Hope that helps