I have an MPC1000 JJOS OX2XL. During a local estate sale today I picked up another MPC1000 (25$). It’s fully loaded with 128MB, but only use JOS1 V5.0. I haven’t had a chance to power it up yet, but the machine appears to clean and very well kept. I’m not all that familiar with JOS1 V5.0… any benefits from having two mpcs1000 with different JJOS versions? I looked at the compare chard on the JJOS site, but all the info is mostly gibberish to me.
Thanks
JJOS1 v5.0 was the first paid for premium version of JJOS. JJ has upgraded the OS since (what now is JJOSXL) and to upgrade from JJOS1 to JJOSXL will still be $123 if I‘m not mistaken.
According to MPC Tutor, the files produced on JJOS1 are not compatible with JJOSXL files (and vice versa).
Here a brief look at the history of the different JJOS versions: https://www.mpc-tutor.com/mpc-operating-systems/
I‘d say, at the crazy price at which you bought the MPC, it shouldn‘t hurt to upgrade the OS. 
Hope this helps.
Just so I’m understanding this correctly… I need to install JJOS OX2SL free version first, then pay, then install the paid version? I have one already with OX2SL, and exchanging files isn’t going to be an issue… just curious if version JJOS1 V5 has anything that might be missing in the newer versions or something people prefer with the older system? That way I can get best of two worlds? I really see no point having to machines with the same upgrade, unless there is an advantage or the JJOS1 V5 is really bad?