Have transports improved for Redbook CD playback?

I think your sort of asking the wrong question. Are there transports better than what you have? Yes for sure. As far as transports improving the pertinent question would be since when? And another pertinent fact CD replay is on the quick decline so not a ton of R&D being done on transports. Did you have a budget in mind?

I have heard and liked the CEC beltdrive transports, they make models at a variety of pricepoints and pop up here used pretty regularly. As mentioned by melbguyone Teac/Esoteric makes the VRDS transports which are very high quality. I would suggest those are both good companies to consider as they make their own transport mechanisms. The last thing you want is a transport with a broken mechanism that cannot be fixed or replaced.