Weboost advertises the trucker antenna to have a 2.5 to 3.5dB advantage, which is a doubling of signal strength. In practice, while it won't be anything near a doubling of distance (that takes 4x the power or 6dB), it should result in appreciably further and/or stronger signals being usable.
I'm posting from the Angeles Mountains at the moment. A/B testing between 4" magnetic and full 3 segment length trucker antenna. Network Cell Info Lite app shows about a 1.5 dB difference, -78 dB and -76-77 dB, 4" to trucker antenna respectfully. (no booster gives an unstable -107dB and no workable data whatsoever) Both antennas result in only in 1-2 4G LTE bars on my phone. The 4" is giving me sporadic data comms. The trucker is not only quicker but is much more stable... enough to stream youtube! Surprising given what seems like a minor dB gain. From the results and being able to post this, worth it!
I'm toying with future enhancements mounting a yagi directional antenna to my Airstream. Many of the campsites I'm going to these days are mountainous and have difficult receptions situations.