The Sixteen Ventures article is a great read. Glad you shared it, Andy.
In my experience, 14-day trials for SaaS products that are used by individuals (no dependencies on other team members) are usually the right length. For products that require 2 or more team members to evaluate together as a team, you can likely expect to have a standard 30-day trial length. It's just not realistic to think multiple users will be motivated the same or work at a similar pace with unfamiliar tools unless there is a crisis driving the consideration of a new product.
Assuming you are in the single-user category, so much of the strategy for effective trial user acquisition (and subsequent conversion to paid user) comes down to a few attributes of your CURRENT product:
1) How 'self service' is it today? If a user can visit your web site, gain a solid understanding of the value your product offers to them, sign up, and then get up and running on their own in less than 10-15 minutes, then you can probably go with a 14-day trial.
2) How sticky/engaged are your beta users? You've hopefully been able to learn a lot about your users' habits and their activity with your product through your beta cycles. If your beta users are logging in daily and completing tasks consistently, you can probably conduct a 14-day trial.
3) How busy is your support site or your FAQ page, etc.? If your current users or beta program participants have been able to work with your product in it's current state without much help or interaction with your support resources, you can probably expect a 14-day trial to suffice. If not, you can probably expect to go longer.
4) What's the use case? If people who use your product get a sense of satisfaction daily (like a to-do list or workout tracker), you can go shorter. If the satisfaction line is crossed monthly (like a budgeting tool or a campaign management product) then a longer trial period is required. People need to validate for themselves what they would be paying you to help them achieve.
Lots of other factors in play, obviously, but the best news for you is that you can change it overnight and roll out a longer/shorter period based on feedback and user stats.
I've worked in the free-trial world as a sales leader for 17+ years, primarily focused on selling to business users. It's safe to bet that more than 90% of your paid users will trial your product (some will not because they will have either used your products before or they will have their license purchased for them by an existing user), and well over 50% of those paid users will need a trial period extension - regardless of length. Just make the trial long enough to encourage people to join, but not so long that your best prospects will get on board and then lose steam because they think they still have plenty of time - then they forget about you.