Paradigm in Wall match for Signature S8/C5 v2/v3

I will be upgrading sometime over the next few years to S8v2's or S8v3's and paradigm c5 center depending on the used market availability and cost. Right now I have RTi12's and am probably about 50/50 2ch Music/HT. I want in wall surrounds for my 7.1 system but don't want to spend a ton. Is there a set of paradigm's that are reasonable that will be a match for the S8/C5 mains? I would like to install those now and then upgrade the mains later. I don't care if they sound great with my RTi12's and polk C5 center. I saw some SA-35's floating around and wondered how they would do for surrounds and match the S8's well enough for home theatre use. The SIG-ADP's look awesome but I can't imagine what they sell for.

Any help would be great!

Long long term plans are a pair of subs to be used in stereo to get down low. I want a SFF sub so I'm leaning towards Fathoms or the Sub25 if it ever hits the used market. What is the best method to have the subs run in stereo mode for 2ch and LFE input for movies etc? I have an rsp-1068, rb-1091's (main), rmb-1085 (surrrounds and center). Center will be upgraded to a rb-1091 as well when I upgrade to paradigm mains.
I would not get too worried about matching your surrounds to your front/center units. If you plan on running music in evenly distributed 5.0/5.1/7.0/7.1 than I can see it but for HT the rears can easily be different. I personally can't tell. As for the sub I can vouch that the fathoms are fine units with way more LFE than folks generally expect from a smaller unit. I have a single F112 in a 12x14 room and its good for me. I think your question about your sub in 2.1 as well as 7.1 will depend your electronics. Lots of experts here but I think it may depend on your receiver and how you integrate with your players and amps?