Yes... and No...

The properties of all solder, like melting point, physical strength, and conductivity depends on what metals are used and the ratios of the mix. Earlier mixtures of silver solder have higher melting points, and over the past few years research into different mixtures has resulted in new versions. The Lead free rules have spurred development of new ratios and new solders.

All the ones you mentioned have lead in them BTW... but Wonder solder does have a lead free option.

The WBT solder you mentioned melts at 180*C vs 183*C for 63/37... only 3 degrees cooler. (about 5*F difference)

Wonder solder melts at 193*C so 10* hotter. (about 18*F) (and the lead free needs around 50*C more, a big jump)

Cardas has the lowest melting point of 170*C (13*C is 23.4*F so this is a difference I would call significant so I concede that this solder is better in terms of melting point and it is eutectic just like 63/37)

Some mixtures have lower melting points, others have higher, and there physical strengths vary, as well as their conductivity.

As far as conductivity... I stand by my statement that the difference is so small as to not matter in the RC world.

Conductivity of the solder depends on the same things as the melting point, the ratios of the different metals.

In the various solder ratios that contain silver that the average person will use... the difference in conductivity (measured in percent of copper's conductivity) is less than .5% to at best) a few percent difference. (3 or 4 depending on mixture) 63/37 is 11.5% and silver solder ranges between 11.9 to 16%, and most hover in the 12-13% range. That difference is too small for you to notice... BTW all the solders you mentioned are aimed at the high end audio crowd and they wouldn't notice the differences either. (just like the Monster Cables $100 6ft HDMI cord works no better than a cheap $5 6ft cord... but some just feel better using the expensive cable)

There are better conducting solders... gold solder scores higher than copper so it is better than 100%.

Indium based solders have the best conductivity other than gold. Pure Indium is 24% and Indium silver alloy is 23%... but they are designed for soldering gold connectors when purity of the connection is vital... and prepare to pay out the rear for it... over $100 for 3ft of it is the best price I have seen. (there is a company called Indium Corp that sells all types of solder, so don't think that roll of $50 solder they sell is Indium based)

The solders you mentioned are costly, here are their prices. (based on what I could find)...

The cheapest US source for WBT 0820 was $300 per pound (sold in .5lb rolls, so two $165 rolls to make a pound... found it from a seller in England on ebay for $170 per pound)

Wonder solder was $50 per pound.

Cardas Quad was $135 per pound. (sold in .2lb rolls at $27)

You go through 3lb of solder a year... I noticed you make RC parts/electronics according to your website.

At $25-30 per pound, I would consider switching to the 63/37 for cost savings over the solders you mentioned. Kester brand with 44 rosin core (their RMA) is a good choice, Indium Corp makes some as well for the same price range.

Seriously, give 63/37 a try, if you have never used it, it will probably surprise you... I would bet it is just as easy to use as the ones you mentioned. Of all the types of solder I have tried, it was the easiest to use, and makes better connections the most other solders.

Other than the significant cost savings it provides... The electrical properties are not much different than silver solders, and the melting point as I shown is better than two of your options, and practically the same as the third. The cheapest you mentioned needs a good deal more heat like I said. And it probably is just as easy to use as they are too.

Edit: Fixed some typos