short eps, barlows... it all so confusing!
I tend not to barlow at all (well cept for doubles) but thats because my only barlow is a GS 1.25 and its pretty crapy.
i'd go the ultima , uo, or shorty if at all but that of little help to you
if you want a planetary ep, get something arounf 6-7mm it'll be rare that you can go above that