Biggles, the beauty of most logbook programs written in the past 10 years is that they can export/import data in CSV or tab-delimited text, and more. All of which are compatible with the latest programs.
I've had an electronic logbook since 1992, and have had no problems integrating my old data into new programs.
I used Logbook Pro until a couple of years ago, but with "waking up" to the Mac
, and now the iphone, I use Log Ten Pro/Mobile. Although Logbook Pro was a very good program, IMO Log Ten is far superior in the sense that its interface with the iphone is far slicker, and the reporting function suits that of many countries.