Lots of people seem to be going to mono tubes or ricor in the front. I just did monotubes and will give a review when I actually get to go for a nice long ride
Before you spend a lot of money, try changing the fork oil to the screaming eagle fork oil. It's thicker and will really stiffen up the forks and change the feel of the front end. I like a soft Cadillac ride and prefer the soft ride of the standard fork oil. I have heard of others that have mixed the two oils to get a ride somewhere in between.
I went with mono's on my '10 RK, wish I had tried the oil change first. Very harsh going into,over bumps. I'm getting a set of Ohlins for the rear and if that works out good I'll look into getting something different for the front. On the plus side the front end dive is gone.
the best is what I have , Motorcycle Metals 49mm Triple Trees for 2013 and older bikes , 2014 49mm forks installed fitted with 30mm fully adjustable cartridges , second best is the 25mm Ohlins 101 cartridges inside your current 41mm forks , from there you have many options at a much lesser cost , you need to decide your budget and how good you really want , do you want the best ? or better than you currently have ?
I will be installing the Ohlins 101 cartridges in my limited this winter. To be honest its more money than I want to spend but we ride 20,000 miles a year so for us it will be worth the hit in the wallet.
I've used drop in springs in the past, but on my RG I used the Progressive Monotubes. It's a stiffer ride, but I prefer a stiffer ride compared to a softer one. The drop in springs were to soft for my liking. To each his own though...
I just rebuilt mine when I changed to black forks, after only a few hundred miles, i noticed one fork is leaking oil from the lower seal.
What will mono tubes cost?
It depends on 1) what are you looking to change/improve and 2) how much do you want to spend. I just wanted to firm up the front end a bit and get rid of the nose dive under braking. All I had to do was put in heavier fork oil and got the results I was looking for.