Honestly, Unless the specific LED driven set outperforms the current CCFL set you have now, there is no reason to upgrade.
Color accuracy, black level performance, screen uniformity, useable light output, and so on are still the main focus on what makes a good display.
Full array back-lit LED systems can and do offer many advantages over traditional CCFL driven LCD's because they have the ability to dim sections of the set while keeping others bright.
LED edge lit systems however, are on a pretty equal playing field with CCFL driven sets. You have to look hard for an edge lit LED system that produces a nice uniform picture however. They will all look amazing with a bright image, but dark images can be a challenge.
The problem is, manufacturers are using the LED edge-lit setup to produce ultra thin HDTV sets. This leaves little room to diffuse and balance the light evenly on the screen. I am sure if a company decided to make a 4" thick edge lit LED LCD hdtv, they could solve most of these problems, but thats not the goal.
In short, the CCFL driven LCD could very well outperform an LED driven set. Only the full back lit local dimming LED driven LCDs have an advantage. Its up to you to do your homework.
If you are purely hunting for somthing bigger, then usually the bells and whistles come on the LED driven sets, and the budget minded sets that remain in production are CCFL. That is due to the manufacturers lineup. That doesn't mean the LED driven system is better then the CCFL.