I read recently that the MoD has relented to regimental pressure and decided to call the new Bn the Devon and Dorset Light Infantry. They will wear the rifle green beret but I'm not sure about the badge or even if they are going to have a back badge.
I think "The Rifles" was being bandied about as the future name for the proposed Light Div super regiment created if and when the LI and RGJ go to a single cap badge and regimental name (the Light Green Infantry Jackets having been vetoed early on).
Word on the street now leans towards this having been put on a back burner, as to all intents and purposes the Light Div cross post like a single regiment anyway so the arguements about the relatively few, but important, distinctions between the two regiments aren't worth having.
1 D and D will become 1 LI and take on LI dress and traditions such as drill. The LI will obviously take on the glorious history of the Devons and Dorsets as part of their county tradition in the same way as they have done with Durham, Yorkshire et al. The LI will also take on the equally glorious history of the RGBW, with about a third of the current 1 RGBW strength going to reinforce the new 1 LI when it forms.
Until then, both the D and Ds and the RGBW are being granted the honour of being designated Light Infantry regiments, effective from (I think) Salamanca Day (22 Jul) 2005 - a day which all the Light Infantry regiments share as a common battle honour (and a battle in which the forrunners of the D and Ds and the RGBW did uncommonly well).
The D and D LI may intend to start wearing Light Infantry green berets and cap badges from that date, with all other D and D regalia staying the same. I'm not sure whether the RGBW LI will change cap badges or berets at that point or later.
The TA LI bn is likely to be (on current plans) called 5 LI. Stand by for everything I have just written to change.