I can not comment on the celestron ep. though i can on Meade, Optex/synta, Pentax, Nagler Pentax ,Nagler and Optex well thats like the difference between a 3000 a hour and a 100 dollar a hour .........
Ide kinda rate them like this
1, Pentax/Nagler (depends on your scope and your needs/wants)
2, Meade
3, Optex/synta
15mm e-r isn't that bad at all, i have seen people use glasses with the meade eps and definately with the pentax/naglers. Yes as the fl goes down so does the e-r, a way to combat that is barlow your eps.!
a 2x barlowed 15mm will produce a 7.5mm ep but with a 15mm characteristics.
a 3x barlowed 15mm will produce a 5.omm ep but with a 15mm characteristics.
There are loads of ep reviews in the ep section of this site, that might give you a insite into other peoples views and opinions. hope that helps.