any experience using bettercables?

Rich I'm assuming that this is an AV rig with 4 (or more) speakers? That being the case, even if you relocated the power amp closer to (two of) the speakers & then ran longer interconnects in lieu of longer speaker cables, you'd still have two other speaker cables that are now much longer instead, essentially gaining nothing.
Routing through a wall shouldn't hurt anything sound-wise & is actually helpful if that shortens the cable lengths or offers some cable protection.
Benefits of using a networked design cable actually become emphasised at longer lengths, because the group-delay of an un-compensated design is compromised more & more as cable length increases. That length-factor is one reason that I use them; the other reason being that experimentation has proved a great synergistic matchup between my amps & speakers with MIT speaker cables. Be aware that, like many other things, not everyone that you talk to will agree with me that networked designs are the most desirable. They are however the best for my situation & may possibly be quite good in yours as well. FYI: One or two others have told me that they like the match of MIT cable between a (solid state) amp & B&W speakers.
You may be able to audition some T2 or T3 or T4 (get the best cable that you can reasonably afford) from Cable Company: www.fatwyre.com They have loaner cables available at low cost (although perhaps not at that long a length) so you might have to temporarily setup the equipment or speakers closer than for the permanent setup. Their loaner fees go into your account & are then applicable to any future purchase.
Audio Advisor sells MIT at discount & offers a 30 day satisfaction guarantee.
Also consider contacting MIT rep. Joe Abrams for some helpful / friendly advice, & perhaps even a good deal on some surplus demo's if any are on hand. Equusaudio@aol.com

I think you would be MUCH better off focusing your resources on picking up a couple of monoblocks which can sit right next to or behind your speakers with very short runs of cable. Your sound will be significantly better....even if you have to run long interconnects from your preamp to the monoblocks. It's just not worth it to spend big bucks on 40ft speaker cables. You might want to talk to Roger Sanders at Innersound (www.innersound.net) about this issue.

The Tarot says Carol Studio Grade silver plated copper, 12ga. Comes in spools...dollar for dollar the best speaker wire. The cards also tell me you better have an amplifier that can control such a cable run.

For other info call Miss Cleo...she tells women who the father of their child is!

What I'm about to write may be regarded as total heresy by almost any audiophile who knows anything at all about the conventional wisdom of speaker cable usage, but here is my recent experience anyway. I too am faced with the necessity for a longer run than is usually considered acceptable, albeit more for aesthetic and financial reasons than Richm53. In fact for the past two years I've been using 28' of QED Qudos-dirt cheap by audiophile standards, but first rate-in a single wire configuration on my bi-wirable Audio Gem speakers. I never tried to bi-wire, largely because the dealer had told me there would be little or no improvement, a position which suited my essentially cheapskate nature perfectly. Within the past six months, however, I've managed through judicious bargain hunting (Well, relatively, as these things go!) to upgrade my electronics significantly to a Joule Electra preamp & Bryston 3B-ST amp. This made me curious to see if bi-wiring might not be beneficial, but to test it out on the cheap, I went to Home Depot and bought 120' of 10 gauge copper appliance wire for a total cost of less than $17.00. I've connected this wire, cut into 30' pieces, to the tweeter posts. The difference is incredible: Sweeter highs, especially for strings; improved soundstage depth and delineation of instruments within the stage; an overall delicacy & airiness which I had never noticed before; better mid-bass definition, etc., etc., etc. In fact it's hard to find fault with the results.

So what does this mean? That you have to be crazy to spend big dollars for cable? That the usual theory about long cable runs is myth? That my system might sound even better were I to try an expensive audiophile wire (Admittedly this is a real temptation, although I've lately become increasingly convinced that interconnects play a much larger role than speaker cable.)? That bi-wiring alone, even with the cheap Home Depot stuff, is sufficient to create a significant upgrade in sound, contrary to the dealer's suggestion (I keep thinking there has to be a reason for the manufacturer to include this capability.)? That-Heaven forbid!-I'm hearing what I want to hear, because the change was so cheap?

Frankly, the answer(s) may be all, some, or none, of the above. I really don't know, nor am I inclined to speculate a whole lot on this (very pleasant) phenomenon, for which I'm sure some talking head out there has an explanation. I for one simply intend to enjoy the results, now that I've passed on my experience.