I just installed Amanda 3.3.9 on CentOS 6 (I've been running 3.X on that platform for years) and noticed that amstatus displays MB figures to 10 decimal places, which is very ugly indeed and didn't happen for me with earlier 3.3.X releases. Example:

backup1.domain:/data 0 3535.6064453125m finished (17:01:24)
backup2.domain:/data 0 24312.0517578125m dump done, writing to tape (11634.15625m done (47.85%)) (22:56:12)

I can't see the point of any decimal places at all myself (the older 3.3.X didn't have them) and I really don't understand why you'd need an excessive number like 10 in 3.3.9...