Barlow?

I was thinking about getting the GSO ED 2" Barlow (Garrett Optics)for my 10" f4.7 dob, as I can use it for all my 1.25 eyepieces too. Could I use that with my 30mm 2" eyepiece to look at star clusters, dso's etc. instead of getting another 2" 15mm eyepiece or would this lose to much light and make the eyepiece quality too inferior for good use?
Thank you