Let me clear up a few things:
The primary impetus for the XL was the FASLINK port. Since I had to develop a new mainboard to support this I figured why not put in some of the other requests we get from the power users.
The additional memory is FLASH which is EPROM not RAM. This will not increase the looper time as the amount of RAM has not changed.
The type of FLASH memory is "Super-FLASH" which is an expensive, high-reliability memory. It can be erased hundreds of thousands of times without wearout or slowdown. This prevents the need to wear-level the memory and the dreaded "Tuning Memory" stuff.
There is no longer any SRAM for preset storage. All presets are stored in FLASH.
There is still a small SRAM for storage of system information that requires a battery. You can still back your system up to FLASH. If the battery dies you won't lose your presets and hopefully you've backed up your system.
There is enough FLASH memory to store 1024 presets and 1024 user cabs but I'm reserving half the memory for future upgrades.
The "Special Sauce III" uses a combination of things to get a lower noise floor. One of these things is new, premium Burr-Brown op-amps in the signal path which have extremely low noise and distortion (and are very expensive). As always I don't design stuff to be cheap, I design it to be good.
The optical encoder requires power and therefore can not be retrofitted into a Mark I/II. Also the shaft and bushing size are different so it doesn't fit anyways.
UltraRes is not specific to the XL and, in fact, the beta testers have Version 13.00 beta now and are testing the UltraRes capability.
All algorithms will be identical between the Mark I/II and XL. They all share the same code base. Any enhancements/improvements will benefit all models except when aforementioned features are not available.
The Mark II will continue to be produced and sold. The XL is a higher-priced option for those who need the features and does not in any way obsolete the Mark II.
