Wife and I purchased a 2015 RTS - Special Series in February. We comparison shopped between that and the limited. The primary difference in these two were the GPS and the luggage bag in the frunk were included on the limited (along with a few more bucks in the price). When we got to the dealer and compared them, we saw that the GPS mount was mounted in such a way that it would be difficult to see the image if you needed to during daylight hours. (Facing up/Glare) We didn't care about the luggage, so that was not a factor.
The only other consideration for us was the color. We really like the Cognac color from previous years and the Black Currant, but these colors weren't available in 2015 (colors of the Limited), so we decided on the RTS-SS. The Limited has the Chrome accents whereas the SS has a matte/brushed chrome look on the accents which we liked better. Wheels are black and chrome, so not all shiny.
Definately get the SE6 transmission, you won't regret that. Attaching a professional pic downloaded from the interwebs.
One more thought, BRP was offering a rebate on the 2015 models starting around late October it seems that went thru the end of January. They lowered the rebate by $500 in February, so we got a lesser rebate. The other thing we did was shop prices around the country online. I took in the advertised price from a dealer in Chicago and my local dealer matched the price. It was a significant savings by doing that.