In short, better performance, longer battery life
you can refer to
https://www.head-fi.org/threads/fii...-dual-card-slot.828402/page-968#post-14797406
to get the changlong for jkbuha's kernel (which I have also extracted below)
Changelog
Version 2.7
New: Redesigned Busybox installer
New: Redesigned Permissive SE Linux installer
New: Kernel version now displayed in settings
Fix: Corrections to anyone who was not seeing the msg "Kernel optimisation Ready" prompt
Version 2.6
New: UKSM instead of KSM (much faster)
New: ZRAM (more RAM)
New: fsync_disable (much, much faster)
New: ROW I/O scheduler for SD cards (much faster)
New: LZ4 Compression instead of LZO (faster, more compression)
New: zsmalloc implementation instead of xsmalloc
New: zcache enabling (faster)
New: ARM RSEM implementation (faster)
New: frandom generator instead of random (much, much faster)
New: MSG pop-up notification daemon
Fix: Lowered voltage for some FiiO players with lower-grade VCOs
Fix: Corrected git file dependencies
Fix: Disabled system animation by default
Previous Versions
Version 2.5
New: Increased max clock speed to 1752MHz (faster)
New: BFQ I/O scheduler (faster)
New: Westwood TCP/IP congestion protocol (much faster)
New: InteractiveX governor (much, much, much faster)
Fix: Stability checks to voltage
Fix: iX handling changes
Version 2.4
New: Maple I/O Scheduler (faster)
New: init.d full support (much, much faster)
New: init.d scripts (thanks prispewnic @ 4PDA)
Version 2.3
New: Zen I/O scheduler (much faster)
Version 2.2
Fix: Changes to scheduler priorities during screen off (faster)
Version 2.1
New: Additional GPU and DDR overclocking (much, much faster)
Version 1.5
New: Update to Linaro gcc 4.9.4 (significantly much faster)
Version 1.4
New: SIO I/O scheduler (faster)
New: VR I/O scheduler (faster)
Version 1.3
New: CPU clock to 1704MHz (much, much faster)
Version 1.2
New: Additional voltage optimisation and DDR overclocking
Version 1.1
New: GPIO optimisation and documentation
New: CPU clock to 1518MHz (faster)
Version 1.0
Initial system release and branch-off from FiiO GPL code