I have a first gen iPad and both smartgo books and smartgo kifu work smoothly. No need to sync.
However I would definitely NOT recommend to buy an iPad 1 for this purpose:
- many apps crash due to insufficient memory (the most noticeable being safari and AppStore! Shame.)
- you may get into trouble when downloading apps because Apple stopped the support of the iPad 1 at IOS 5 and many apps require a more recent iOS version. For instance go books requires iOS 8. You may download a former version of the app but this might be not straightforward or even might be not possible, see:
https://discussions.apple.com/thread/5519108?tstart=0
- even if you are able to download the app, you will not get the last version of Go Books, since iOS 8 is required for this and Apple stopped the support of this model at iOS 5. Consequence: you won't have the most recent books (15 are missing as I have seen).
- the battery of your IPAd 1 will certainly have gone through many cycles, so need to change it quickly. I don't know if Apple still supports battery change for this model and it certainly is not worth the cost.