Well first off eye stain isn't related to power of your bins but more so to the quailty of glass and more specfically the coatings used. For example my 8x43 pentax SP gave me more eye strain then my 10x swaro el's. The pentax areno slouchesbut they just can't touch the EL's optically.

As to why 8x less critical to hand shake, easier to find target (especially close range), they transmit more light, lesser quality bins show less optical flaws at lower power, etc.Weight, styling and the fact most people don't use bins for truly long range are other reasons why7 and 8x are popular and available. Personally unless your willing to pay 500or upfor bins I would suggest 8x's. If your budget allows you to get to say 550-650 check out cameralandny I just received an email today about some SHOT specials on bins.Doug has Minox HG's for around 550 on sale, i picked up a pair of 10x43's for my Dad last year and they are very nice for this price. He also lists some Vortex razors models though I can't recall the price off hand.I haven't had a lot of eye time with these but what iI have had they aresimilar to Minox performance. However from some of the reportsI have seen from guys who have really gave them a look over they may even be a touch better...Swaro feel/look to them. IfI could convince my walletI need to buy a pair I would just b/c. I would like to see how they stack up.