The amount of work involved is conditional upon the number of presets that are dependent on older firmware for their tonal characteristics. Personally, I think selectable firmware is a stroke of genius on Cliff's part and solves the issue.
If the willing is there, expanding the lifetime of MK1/MK2 - and i assume it is ... I second the idea of decrease the baked in factory Cabs, if they use the same memory, which seems getting out of memory. Who use NON UR cabs these days anymore? A minority, i assume. And for those, this data can be supplied as external User Cabs, IMO. So, in fact, NOTHING would get lost. As long as this data would be supplied as .IR format, it would be only usable for Axe-Fx II devices anyway. Or the hard way: Customers do tonematches of those old HiRes Cabs and save them externaly (User Cab export). The quality decreasement from 2048 samples to 1024 samples, the tonematch provides, should be negligible (If the RAW tonematch data is not even longer, when exporting as user cab, don`t know). Even more negligible in relation, when thinking about, what the longterm investment guys of MKII Users will win, due to longer algorithm improvements in the Amp department.
Secondly i second also to get rid of choosable Amp modelling selection, although it would unnecessary limit the XL / XL+ users, BECAUSE: Amp modelling selection was and is always a concession for a small group of people, who likes the "old" FW modelling better.
But in fact, it just increase time to adapt their tones to the current modelling algorithm, because the oldest modelling selection disappears anyway, when newer and newer Firmwares came out.
Especially MKII customers, who bought their unit in the time, MKII and XL were parallel newsworthy did a longterm investment in trust beeing up to date with the modelling technology also in the future, because it was always the underlying statement (at least to me), that MKI/MKII & XL/XL+ were basically the same Axe-Fx II family, although the introduction statement for the XL promise, that in the future it COULD happen, that certain improvements will be XL exclusive:
From the XL Introducing (2014):
http://www.fractalaudio.com/announcing-axe-fx-ii-xl.php
- 128 Mb of non-volatile Super-FLASH memory allows for storage of up to 512 presets and 512 user cabinets with copious reserves for future expansion.
- Double-capacity preset size allows for expanded functionality including X/Y switching on more blocks and more instances of effects.
It was always stated, at least in my understanding, that the modelling of the MKII and XL will be the same. The two feature statements did although suggest, that the spread of feature set between MKII and XL could increase in the future. But more for more preset memory, user cab memory, new FX blocks, more block instances, more scenes, more ... blahblah, but not the heart of the unit: the quality of the amp modelling.
Personally, I´m still on the trusty MKI unit. And i am extremely satisfied with (apart the fu`ing loud 60mm fan ...), very happy and thankfully about the improvements in the last years and would be not disappointed, if my unit would be EOL in a short term view, because without a doubt: It is a awesome unit as it is now