I would not agree that the S670 is perfect for home use, it is £500 in the UK which puts it in the low end of intermediate grade Arrangers.The PSR S670 costs over a grand in Australia. (something like $1200 thereabouts). I would hardly call that a budget item.
The features and sound output of this model are supreme to my mind and having built in speakers makes it a perfect choice for home use. I intend to upgrade to this model oneday soon (maybe!) Depends whether I want to change brands or not. My shopping for up grade has not started yet!
Anyway as I stated earlier, If spending a grand you would expect perfection. A flat and level keybed is essential! I am glad Jimmy got his money back.
If we assume that the likes of the E353 and E463 and equivalent Casio models are at the high end of beginner keyboards then surely the market changes above the E463.
The Roland BK 3 and 5 models would certainly be Arrangers of choice imho in the price range of the S670 with the Korg PA600 being at the top end of the price range. All three non Yanaha models I quote are certainly of superior build quality to any of the Yamahas in the price range and arguably of better sound quality and most certainly easier and less problematic interfacing the, into a home studio environment.
It is a pity that Arrangers in this price range are limited in makes and it is where Yamaha win, they flood the beginners market and hook newbies at the start of their musical learning.