I haven't personally sat on an X-300, but have a lot of seat time on bikes.
My finding is that seats the are squishy and comfortable for 10 mile rides suck big time after a few hours in the saddle because you sink to the seat pan over time.
Seats that are uncomfortable for 10 mile rides are all day comfortable because they slowly form to you but never lose support.
Of course some seats never work for me which makes it hard to spend the money. At least Harley lets you demo the seats before you purchase.