Mine is pretty close. I have a calibrated hygrometer and the AC humidity sensor reads two degrees below. I think it's close enough to call accurate but I would suggest getting a unit to compare and calibrate one or the other.
I looked for the foam clamp style connectors. I found them under duct anti-vibration clamps. However, very few places carry them and shipping was beyond reasonable. If you should find one locally I think they look ideal. Aside from that, aluminum tape is probably the easy and available choice with a bit of flex duct cut to fit.
@Qbgrower - Thanks for the heads up on the fast clamp style connectors with the foam backing. I did not know these existed.