I may have too many eyepieces for my XT-12, 1500mm focal length, f4.9.

Included in my eyepieces are a 10mm Radian and a 5mm Nagler Type 6, and, a
TV 2X Barlow.

Do I need the 5mm, or, will the 10mm with Barlow provide the same results?
Views through the 5mm are really crisp and bright -- will I lose anything
with the Barlow?

Thanks.