Unless it is a blind test, neutral is not possible.
That aside, listening for yourself is always best.
About price: it means very little. The Ref. 1 has been on special for $600 in the past. This is not a slam on the speaker--I have never heard it.
As I said earlier, it will cost you very little to try both.
I am not at all neutral--I own the Sierra-1s, and I think they are fabulous. I upgraded from the 340SEs, and I did a ton of listening before I bought those. Some on my list: B&W 602, Paradigm Studio 20, Usher S-520 and V-601, NHT Classic Threes, Tannoy something or other, M & K, Vienna Hydins, Monitor Bronze, Totem Rainmakers, Era Design 4.
There's more, but I don't remember any more. To me the Ascend 340 was the best, and I did direct comparisons to the Classic Three, Totem, Ushers.
I also did direct comparisons between the 340 and Sierra. I think the Sierra is worth the extra money. Their bass extension is remarkable, and totally clean. In other areas I would describe the difference as the 340 having a thin layer of gauze in front of it, compared to the Sierra. The Sierras are smaller and better looking--mine are natural bamboo, which is a terrific material for a speaker.
Few people have performed more due diligence than I have in researching speakers in the 500-1000 price range. I have earned my opinions.
And they do not mean a damned thing.
The only "fact" is that I am happy with my decision, and that I do not have the slightest buyer's remorse.
About A/B testing, you can guy an A/B switch from Radio Shack. To be perfectly fair, you will need an SPL meter so you can level match the speakers. I did this in my house and it worked well, especially when I had speakers that seemed pretty similar.
The switch is nice since you will be able to flip back and forth quickly, unless you have only one pair of stands and need to switch speakers.
I have not read about a direct comparison between the Ref. 1 and the Sierra. There are a lot of people who would like to hear about it.
Where are you located, btw? You might be able to find an owner of one nearby which could save you some money.