We've gotten a few weeks extension, but at some point I'm pretty sure things will be enforced.
Regarding Paypal, I believe the fraud that hurts the most is credit card (chargebacks, threshold maximums and card programs!), and Paypal in general is not that bad at that (not as bad as other things).
If Sift sticks with their new pricing, I think it comes down to doing some math.
Our Current Sift Scenario: 3,000 USD a year.
Proposed Sift Scenario: 12,000 USD a year.
Potential Stripe Radar Only Scenario: 0.
Assuming Stripe is as good or possibly better than Sift at catching fraud/automating flows, then we've got 3 to 12k to offset any potential PayPal fraud and still come out on top.
Ok, Not proper math, but worth considering...
Edit: formatting.