Does speaker cable length really matter?

I need to change from my 8' Harmonic Technlogy Pro-9 Bi-Wire to a 12' Pro-9 Bi-Wire and wondered if I will notice any significant differences?
Most cable Gurus prefer longer interconnect to amp, as oppossed to long speaker cables. Every system is different cost wise depending on your cables, but for HT 12ft of Pro-9 speaker cable will run you $1180 new, and 12ft of Truthlink interconnect will run $555. Ideally empty space would be between speakers to maximize imaging and soundstage, but I have small equipment rack against rear wall centered between speakers which are pulled out 5ft from rear wall. This keeps all my cables and interconnects short, but I give up a little soundstaging with rack in center....Regards Sam
Thanks guys,I have installed the 12' cables and they are breaking in as I write. So far they don't seem to have any negative affects. sam, i'll think about your advice in future applications. Appreciate all the help here. Bye for now.
The other advantage using a long interconnect to amp run as opposed to long speaker cables is that you can use balanced cables for the interconnect. Though I don't think that XLR helps a lot in short lengths, it does in long ones since most interference that the wire picks up along the way (antenna effect, EM inducted currents...) should be cancelled out by the balanced cables. Speaker cables can't do that. Also for most cable questions check out They have a great tech section where they explain a lot of the physics involved in cables.