That's a bit specious. Have you actually tried them?

Syncronizers also weight LESS than .6 oz so weight doesn't even come into play.

It's more likely that you'll screw up a mix, and ruin your plane than the syncronizer will fail.

The lag and end point differences do affect the plane's performance, which is one reason syncronizers are so often used by Giant Scale & Gasser pilots for the same purpose...

There is a lot of expensive equipment in those planes relying upon syncronizers.

With larger 3D planes I'll take accuracy and quality over lag and shortcuts any day.