Bi-Wire

Bi-wiring speakers doubles the cable going to the speaker - if the speakers are biwireable then each set of drivers gets a cable thus being driven individually from the amp with the same power going to each speaker - channel a and b do not go to the same speaker - L (a) channel goes to the left and R(b) channel goes to the right speaker. Some amps make it hard to run that amount of cable from its speaker out posts. If it is easy then there may be improved sound that comes from the speaker - this is always a source of great debate. Some confuse biwire with biamping which is a totally different story.

After several researches and trials, I've realised that biwiring your speakers can bring you more disadvantages than benefits since it changes an equivalent circuit of speaker-crossover combo. Another words your speaker cables become more to participate as a part of a speaker-amplifier circuitry adding more reactance. Reactance is non-ohmic components of overall impedance which we usually do not want to deal with in ideal case.
My first and the last experience with bi-wired cables was the following: I simply used the same cables in the single-wired setup in different positions: lower binding posts -> jumpers to upper binding posts and the same with upper binding posts and then trivial bi-wired connection. The first result brought me forwarded bottom and lower-midrange. The second result brougt me forwarded top-end with upper-mids which is certainly much brigher than the previous. The third result was balanced but everything was too airy with no presentation. Finally I've sold biwired and staying with bare wires threaded through the holes of the WBT binding posts of my speakers with no jumpers -- simply the best connection that I could think of.
Extra pairs of binding posts on your speakers can give you an advantage of biamping them rather than biwiring. There are some ideas to use for bottom end one pair of single-wired cables and for top-end another pair with best-on-your-ear matched brands -- at least that makes more sence to me than just blindly buying bi-wire cables IMHO.

Marakanetz: I've read your post three times and I think you had things backwards or confused.

If you were running the speakers with the jumpers on you were not bi-wiring. (even if you were using Bi-Wire cables). The use of the jumpers negates any benefits, and makes your speakers the same as non-biwire speakers.

Now you are running separate single wires without using the jumpers in the binding posts. This is exactly what bi-wiring is.

If this is correct, then you may unknowingly believe bi-wiring helps.

Bi-Wire speaker cables are just combined in a single package as opposed to running separate cables to the speakers. This is called single bi-wire cables. Double Bi-wire is running separate cables for the top and bottom. Some companies make special bi-wire cables that are double the single cable in one jacket (MIT, Analysis Plus Bi-Oval, Nordost and others); These cables cost more that the single version, because there is more cable. Many use different size conductors for the top and bottom very much like you mention using using different single cables.

Other companies separate the mulitple conductors in their regular single cable version into four conductors at the speaker end (AudioQuest, Straightwire, Blue Circle, many others). These cables only cost a little more than the single version (more spade or banana terminations needed). One system of mine has double Audioquest even though a single cable can be made into a biwire. This is more costly because you need twice as much cable. For the regular single version audioquest uses the larger gauge cables for the bottom and the smaller gauge for the top.