The redesigned PSAT is actually moving more closely in line with the material and format of the ACT. Therefore, a student who does well on the redesigned PSAT should not immediately assume the SAT is a better choice. It may indicate that the redesigned SAT would be a viable option but not the only option.
It is still best to also take an ACT diagnostic exam to see how you really do on the ACT and compare it to your PSAT score. If you score very poorly on the ACT diagnostic, especially in Science, taking the redesigned SAT may be worthwhile because the new SAT will not contain Science.