Hi Steve
I have the 8x and the 10x GPO's. You are right to caveat facial differences and only a physical test will determine their suitability for you. I did notice the occasional blackout on the 8x32's when I first got them but a bit of IPD adjusting and repositioning resolved it completely. Strangely enough the 10x never showed any blackout whatsoever. I don't wear spectacles, my wife does and she had no blackout problems from the gitgo.
I recently took both bino's to test against some Leica Trinivods I was offered at a very attractive price and the GPO's bested them for CA and eye relief and were neck and neck for optical quality. I did find the Trinovid 8x to be susceptible to blackout just like the 8x GPO's but again a bit of jiggling with the IPD sorted it. Again it is down to how you hold them and your facial profile.
I bought mine having been delighted, nay frankly amazed, at some Geco's (same bino's, different badge) I had bought previously and wasn't in the market for L/Z/SW bino's at that time. But, whilst clearly not in the oft quoted 'Alpha class', they are not a million miles behind. They are exceptionally well made, the eyecups and their adjustment makes my NL Pure's look positively agricultural and the optical quality is excellent. At least to my eyes.
I bought the 10x and the 8x32 GPO's from the quite superb James Bix of Stealth Birding last year and frankly they are amazing bino's. He often has discount promotions and it is always worth a phone call to get the best price. (His returns policy is excellent should they not suit you).
The only question I have for any of the GPO/Geco's I have in my collection is how do they do it for the price?
Pat