I agree Geoff and was thinking that after I read the review but didn't want to post that comment.
I wasn't endorsing the S500 15mm, just stating the results as I've never used a gs ep. The 15mm S500 is good for the kids and tourists, but the shorter (6.5 and 4mm) f/lengths dont stand up too well for this as even the kids have made some comments and we use other better quality options for higher mags.
A comparison for the Budget eps should include the 25 and 30's as well as the shorter length 6 and 9mm eps. Someone starting from scratch would have a more informed choice in selecting their first eps