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PianoMonk If one was wanting rhythm accompaniment, the Casio choice in that price range is the CTX700, but the keyboard is rather noisy, from some reviews I've read.
I didn't even know a CTX700 exists, actually I didn't know the CTX line exists. Seems like Casio is blurring the lines with the CT400 or CT500 models. From what I can tell as difference at a first glance, the CTX700 has a bigger housing (similar Yammi E373) with more buttons than the others.
I am happy I didn't know all the alternatives, when I bought CT-S1. I just read in PianoWorld the CT-S1 has the most piano-like action-feel amongst the cheapo lightweights like the Go:Piano and similar priced Casios. I liked the small form factor and the look of the nice fabric over the speaker section. Now I use it when I am at my parents place. It is not a piano like my CN29, but still good eough to learn Blues licks and to program my musclememory. Considering the price and portability I am quite happy with it.
If I had also considered the Yamaha alternatives, I would not have bought one until today, but would still linger around in internet forums, reading reviews and watch comparison videos.