U123 or U100+?
are they of about the same spec? with 9 cell coming as a package?
U123 is the latest release, similar in specs but different in design. 9-Cell currently not available for U123 yet. However, just to note, U100 & U123 uses the same battery.
U123 has the same specs as U100 Plus, but the even newer variant (U123H) that arrived only just today, comes with in-built HSDPA (3.5G) module.
9-cell battery if sold separately, costs SRP $199 w/GST.
P.S.: All sets are equipped with 6-cell battery unless otherwise stated. (For eg. U100 Plus-E: 9-Cell)