The best thing about Thinklab is that it not that it solves a major problem in science but that it solves most major problems in science. Having used Thinklab for over a year now, I have experienced the plethora of benefits. However, I think the OSP proposal is lacking specificity and details. My worry is that the reviewers may not fully appreciate the platform's potential.
I have a few specific recommendations.
Mention Thinklab's current successes: How many projects and proposals are there currently? How many users? How many discussions? How many comments? Are there notable achievements? Are there any lessons you've learned in the past two years that are shaping your future plans?
Infuse more examples: There are many assertions with little evidence presented to back them up. While you may consider the statements intuitive, it will help solidify the concepts in readers' mind if there are examples. Are there past events that reinforce your vision of open science? Stories that the readers will be familiar with that Thinklab addresses? The proposal needs to be more data driven and evidence based.
Add citations: I think some reviewers may desire more citations. The lack of citations and examples makes the project seem detached from the rest of the open science movement. Citations also lend credibility to your statements.
There are several repetitive statements throughout the proposal, which can be refactored out to accommodate the details.