Currently it has been pushed a little back, because we are focused in the IOs support for XE4. This means not only making it work in ios (which already does), but also a lot of optimizing the code so it work in less powerful devices, using less battery. Currently we are aiming at reducing the memory usage 4 times for example.
So we will be doing a release very soon with IOs/XE4 support, and the reporting engine should be coming after that. Sorry about the delays
Actually you should be able to use FlexCelReport (v3) with XlsxAdapter (not XlsAdapter) and it should support more than 64k rows (of course, you need to save the report as xlsx, not xls for this to work).
FlexCelReport v5 is a bigger change, it includes things like conditional tags (<#if(condition;<#tag1>;<#tag2>)> and a lot of new features like includes (you can include a report inside another) or expressions (a collection of formula tags that you can reuse without typing them every time) and a whole bunch of new stuff. One of the reasons for the delay is that we don't only need to finish testing it, but we also need to deliver a converter so you can migrate the v3 reports to v5 automatically. But the xlsx and row restriction is not a reason for the delay, the current v3 FlexCelReport will work fine with more than 64k rows as long as you use XlsxAdapter (and save as xlsx)