DM-42 and WP-43S

[bhtooefr]

The simple answer is that, once you're used to the older behavior, it's faster than the newer behavior for many operations, especially with the stack replicating at its top level. (Of course, if you're NOT used to it, or you're doing something that logically works better with more stack... But the older enter key behavior is never slower once you're used to it (the quickest (although not the most efficient stack utilization) way to square on a RPN calc is ENTER *, but on an RPL or Entry RPN calc, it's either a shift and x^2 (slower when your fingers are down on the number area), or ENTER ENTER *), and I rarely run out of stack.)

And, there's another project to recreate an RPL environment if you want RPL - newRPL. I suspect it'll end up ported to this hardware. These firmwares are for people who want the 41 and 42 behavior.