Are there disadvantages of heat shrink tubing with higher shrink ratios?
One small disadvantage I've found is that the wall of a high shrink ratio tube can get quite thick when shrunk.

If your joint has some small diameter sections then the high ratio tube might shrink all the way, conforming tightly to the wire, and become quite stiff compared to a 2:1 tube.

There's also a problem of asymmetry. If the shrink-er doesn't use an air deflector or turn the joint while heating it, one side of the tube will shrink first, making it asymmetrical. A 2:1 tube suffers less from this as it can't go so wrong.