For the most part, using a Spider Jam or JM4 Looper with a Mac is simple and straightforward.
As a die-hard Mac user since 1984, I have had no problems whatsoever with using my Spider Jam with my MacPro. I have had none of the SD card problems that seem to plague Windows users. The firmware releases 2.07 and 2.07 both downloaded and installed first time. I have had no problems with formatting, reading or writing to any brand of SD card I have tried.
Line6 provide a MD5 Checksum Utility for Windows users to check the integrity of firmware downloads but have not provided a similar utility for Mac users. Maybe they think it is unnecessary but I have written such a utility for Mac (OS X) and you can download it for free.
Now, there is just one small issue that has come to light regarding the PC-centric nature of the files saved by a Spider Jam or JM4 Looper. They use an antiquated MSDOS format - because it is an 'industry standard'.
Firstly, the WAV format used is not a native audio format. The Mac audio equivalent is AIFF but this is of minor concern as QuickTime can handle WAV format seamlessly and every Mac has QuickTime by default.
Of more concern is what happens when you copy a WAV file from a Mac onto an SD card and then put that SD card into the amp or looper. When you scroll down the list of files, you may not see what you expect. That A minor slow blues.wav will have been truncated into something like AMNRSB'1.WAV and there may also be a file called _AMNRS'1.WAV. MSDOS uses something referred to a 8.3 file-naming convention. The .3 at the end is the .WAV extension. The 8 is the eight character truncated filename. Only A-Z, 0-9 and the underscore _ are allowed. If you rename your files to suit this convention, before copying them to the SD card, you will get what you expect - except, what are those duplicate files starting with an underscore? On Macs, files you save have two parts. One is the data itself. The other part is called the 'resource fork' and holds things like icons and images. When you copy a Mac file to an SD card, the data and resource parts are split into two separate files. The data part is the sound file that you want and the file beginning with an underscore is the resource file that is redundant but still shows up in the list.
Be warned that any attempt to load or play a Mac resource file will result in a crash. The amp or looper will be very confused as nobody has told it what to do with such files - such as simply ignoring them. It will go off in a huff, freeze-up, refuse to have anything more to do with you and have to be rebooted.
There is no provision to delete these files either within the device - they don't appear in the list of deletable files - or on your Mac because they don't show as separate files in The Finder.
All you can do is ignore them! They won't go away but they won't do any harm if left alone.