The main difference between them is the width of the strap. The biggest of the lot is Slide, which is for DSLR. Slide Lite is for smaller DSLR and mirrorless cameras while the smallest of the lot, Leash, is meant for smaller cameras.
Bought Crumpler’s Photo Neck Strap, The Industry Disgrace, at Raffles City’s Crumpler Store for S$25. I have no idea why the website put S$34.24, I think must be an error or the price was reduced.
Conclusion, it is definitely worth the money as you will feel the difference between the stock neck strap and this one. The latter is much more comfortable because of the design and the cushion padding at the back.