Unfortunately you can't run v5 and v6 concurrently on the iPad as downloading v6 updates v5.
I successfully ran LTP 5 & 6 on my iPad2 last night, duplicating the entry for the day's flying. LTP6 has downloaded as a separate App, not modified LTP5.
As to iCloud sync/backup, iCloud ate about 40 files of mine on Friday. All of my Pages, Numbers & Keynote files have disappeared. Apple Tech Support advised that I wouldn't hear from them for a few days on the issue because of a backlog of iCloud issues from other customers.
