I like the PL-330 a lot. In my experience, for SSB reception there is very little difference between it and the PL-990X. The main performance difference might just be the length of the built-in telescopic antenna, it's 100 cm extended on the 990X and just 49 cm on the 330. In any event, the PL-330 is a pretty amazing performer on SSB for what it costs, with 10 Hz resolution and good frequency stability. What portable shortwave radio had SSB with 10 Hz resolution in the old days? The answer is none, I think.
The only smaller radio that might outperform it is the Belka, but early versions of the the Belka didn't have the AM broadcast band and current versions still don't FM. For a travel radio, I think you really need both AM and FM.
The only thing I don't like about the PL-330 is the build quality. I've had mine for less than a year and the knobs are already a little wobbly. I would love to see Tecsun put this same radio in a solid metal case of the same size, with high quality tuning and volume knobs that were a little easier to turn. It would be a little heavier and more expensive, but the improved durability would be well worth it.