The current 24-105 f/4is is a very competent lens that will be with us in its current form for quite some time. I bought mine after a staggeringly disappointing run of four sub-standard 24-70 f/2.8 zooms, and it's an absolute cracker, pin sharp wide open and useful IS. What's there to change? The optical issues are corrected automatically on import into LR4. I thought I'd be selling the 24-105 when the 24-70II shipped, but this one is a keeper.