I
The only reason i'm going for spacers is because I really like the ride quality of the stock Ram Rebel.
It's so much better than my last two cars, which were a 4 Runner with Icon stage 3 suspension and a Tacoma with the 6112 in the front and 5100 in the rear. I'm not trying to mickey mouse but i'm hesitant to upgrade to a new suspension and change my ride..
In that case Fox 2.5 DSC would be my recommendation.
dial the adjusters to the lowest till it locks and then go back one click. I ride at max out low speed and it soaks up all the bumps and stuff on pavement while still allowing me to corner and go through canyons at a reasonable pace (aka, i'm overtaking all the tourists and weekend drivers)
at the current setting my butt is telling me it's an improved ride over stock since it takes out the floaty-ness of the stock ride.
I also noted that you wanna do 35s. Keep in mind 35s are heavier than stock 33s, and that is unsprung weight which translate to a lot more than what the difference is for suspension. It's a whole lot of explanation and science and math behind that is complicated to explain. You can YouTube unsprung weight if you want.
35s and their unsprung weight will affect the way suspension reacts, meaning the wheels and tires now have too much weight for the suspension to react to without negatively impact your ride quality. This is because of valving is NOT valved for that much unsprung weight.
35s with 5100 should be better in your case, since 5100s have a firmer valve than stock 4600s. That firmer valving is designed to handle larger tires and their unsprung weight without negatively impact your ride quality. So yes, 5100s will ride firmer on 33s.
If you like the digressive piston of your 4600s, keeping it within Bilstein should be a great choice.
spacers are not the way to go. you are basically limiting your suspension travel to get that "lift" and further messing with your suspension ride and geometry. That will NOT net you what you are looking for.