I wouldn't worry too much about the brand of synthetic underlayment.
When I did my roof this summer I tried to research synthetic underlayments, and I couldn't find anything that says there is any significant advantage to synthetics versus felt, or any particular brand of synthetic versus another once the roof is complete. There are advantages for the installation itself, but once the roof is done, it's the quality of the shingles and installation that will make the difference on your roof.
Unfortunately with these types of new building materials, it takes several decades before you know how well they worked. So come back and ask somewhere around 2030 or 2040 and you will get more informed answers.