Here is the comparison in sky at night if you are interested.
http://www.vixenoptics.com/PDF/lvw_review.pdf
I doubt you would be too upset with a 10mm Pentax!
Like Paddy says - think about what final magnifications you are after and how you can make it work with your barlow.
Hope you enjoy the GSO 12 - a great scope.
Cheers
David