I have seen the questions on TOS. I would prefer this forum to collect data, then you could compile a single document to be stored forever in the MoHPC and on TOS.
Here is my feedback regarding the MLDL2000 to your questions:
Battery life: about 8 mA extra when the HP41 is running, less than 1 mA in standby
Module support: virtually no limits, but knowledge of HP41 architecture required. both ROM and ROM emulation (mcode development) supported. HEPAX limited support (like in 41CL, special configuration needed).
Communication: Module images to be up- and downloded using Windows PC with special program (M2kM) using a USB connection. No Linux support (tried, but could not get the USB support properly running).
No serial port, but USB. Serial port possible with V2 prototype, but not implemented.
Settings: Controlled by PC software M2kM, no special ROM's needed to control MLDL2000
Storage: FLASH and SRAM storage for many ROM images. Switchable via PC connection or dip-switches on unit (8 configurations possible). Mass storage possible on MLDL2000 V2 prototype, but this will probably not happen. microSD support an USB comunication planned as extension to the HP41CL
Compatiblility: works with all HP41 variations, including CL. Can co-exist with Clonix if correctly configured.
Mcode development: YES, offline (with SDK41 and M2kM), and inline with DAVID assmebled for example
Learning curve: somewhat steep, knowledge of HP41 architecture required
Documnentation: all details available, inlcuding all sources and schematics
How to buy: sorry, all units sold out, no plans for further production runs or a new version V2 (unless I get an offer I cant refuse ...)
Meindert