First of all, I would get what you want, and I have a couple of friends who are very happy with their Blaser O/Us. While this is not meant as criticism, you did offer how you were planning to set up what you were intending to get, and I personally, can't imagine a more freakish clays gun.
With respect to barrel length, 34" is at the very the far end of the scale. Sort of like deciding your skeet or quail gun should carry 22's. I shoot a lot of box birds, which is the most demanding long range game of which I am aware, and 32's are about as long a set of tubes as you will ever see, and 30's are much, much more common.
I don't get all the other adjustable nonsense either. The very best clays shots I know (consistent mid 40's/low 90's) use none of that sort of gadgetry. Indeed, I find it hugely ammusing watching the occasional add to one of our groups, who is so equipped, playing with combs, butt angles, and choke tubes while target after target is dusted by well balanced, very simple (though not necessarily inexpensive) SxS's or OU's. I can't imagine adding weights to the mix.
One see's more of this, particularly since pre-mounted guns became acceptable. I presume this is a carry over from the skeet fields where such tweaking must help some in such a repetative game. Though there too, it seems more a desperate search for that last 1/8" that will magically elevate someone from average scores.
I am sure that is not the opinion for which you were looking, but you asked, and it is exactly what I would be thinking if you joined our group for a round of clays with such a beast.
