Fair enough, but they have M1 as a baseline so if "M1X" offered very little benefit, I don't see them going forward with it, instead waiting for real benefits with "M2" (the next generation of Apple Silicon on Mac).
If people are expecting the M1X machines to thrash the M1 at “general” tasks that
aren’t optimised for multi-threading or GPU-based computing then they
will likely be disappointed... Just as you would be with Intel if you paid top dollar for a Xeon or i9 extreme and expected Excel to run more smoothly. That’s not what the M?X processors are for.
(I’ve said before that Apple really need to dump the M?-suffix naming scheme and establish a separate branding for their “pro” chips)
For a lot of “pro” apps - media production, scientific computing etc. - which tend to be optimised for multi-core and/or GPU based computing, doubling the number of CPU and GPU cores will likely have a more dramatic impact on performance than moving to a slightly faster core design - in some cases, perfomance could almost double. For those cases where jobs actually
need more than 16GB of RAM, more RAM could also have a more dramatic effect than
slightly faster RAM. More external displays and maybe more Thunderbolt ports are also essential for some.
Going by the rumours, the 2021(ish) high-end Macs are getting the M1X and the 2022 Air is getting the M2 - that means the M2 will
be optimised for ultraportables and tablets which probably means that size and power consumption will be the priority - not a huge increase in the number of cores. It might also make sense to keep the restrictions on displays, max RAM and I/O - which aren’t really a big issue on an Air or iPad. Maybe there will be a M2X a year or so down the line, or maybe the “X” will skip a generation (since it will sell in lower numbers and Pro customers wont want to be the ones to debug the new core design).