The 151 can do 50/60 Hz, the 150 is 60 Hz only. Lens has about the same angle of view. If I remember correctly, ~28mm vs. ~29mm the XF has.And what features are missing on HMC150 compared to new Canon. It works in PAL and NTSC without the need to spend another 500 bucks for an upgrade. Plus it has much wider lens, which eliminates the need for converters.
http://en.wikipedia.org/wiki/List_of_Panasonic_camcorders#AG-HMC150