Segrott

I am in the market for new pedals, I have narrowed down my options to these two. I currently have SPD-SL but I am going to look for something a little different this time around.

Does one pedal have a distinct advantage over the other? I know the Impacts are a little heavier. Does anyone have both of these pedals? if so you feedback/experience with them would be great.

Cycling Giraffe

I have them both. Actual feel when you're clicked in is almost identical, which makes sense since the actual cleat and interface are nearly the same in both pedal systems -- only the body/spindle is really different (in fact, my RXS cleats work fine with my Impact pedals, which is a nice bonus -- I can easily use the same shoes on both my "poser" bike with the RXS and my "workhorse" bike with the Impact Mags). The Impact Mags are a little easier to click into (hard to explain -- just seems to be a more positive "click-in" feel), and, I think because the body is heavier, tend to fall into the "nose-up" position more readily. Bearings feel slightly smoother on the Impact Mags as well, but I have steel axles on those, and Ti axles on my RXS Carbons, which may account for the difference. I have heard some people have problems with durability of the RXS pedals (snapping the front end off, body separating from the axles, etc.) but mine have been fine so far (only about 1000 miles, though). Also, it seems that the non "carbon" versions of the RXS pedals are a little more prone to these problems than the "carbon" versions. On other factors, the RXS pedals are much cooler looking, and quite a bit lighter in the Ti/Carbon version I have. The painted body of the Impacts show wear more than the plastic/carbon body of the RXS. On the other hand, I picked up my Impact Mags from Competitive Cyclist for $85 or so, which was less than half what the RXSs cost me.

Like you, I came from SPD-SLs, and I much prefer the feel of the Time pedals' float -- very precise, smooth feeling float with a bit of resistance, unlike the almost sloppy loose feel I had from the SPD-SLs. In all, I prefer the Times, and consider them a worthwhile upgrade from the SPD-SL.

Between the two Time pedals, just based on my experience, I would just choose whichever one you can better afford; I like having them both, like I said, so the Dura-Ace-equipped uber-bike gets the expensive RXS Ti/Carbon, while the 105-equipped bike gets the Impact Mags. It wasn't worth the extra money for the weight savings and "cool factor" to get the RXS pedals on the workhorse bike, but the RXS went better for my "state of the art" rig.

The Octopus 

I have both (RXS on the tandem; Impact on the single bike and the fixie (and SPD on the commuter)) and I really can't tell much difference between them. If you care overly much about what stuff weighs, go with the RXS. Otherwise, Impact. One other though might be if you're prone to pedal-stike from super-aggressive cornering (guilty here...), the Impacts are beefy enough to withstand that repeatedly. As I want to continue being married to my tandem stoker, I've never whacked a pedal on the tandem, but I wouldn't think the RXS pedals would take much of that kind of abuse.

Segrott

This is the exact reason that I am steering away from another set of SPD-SLs.

At this stage I might lean more towards the Impact Mag as I have read a few posts around that the RSX pedal body has chipped and broken in a few cases. The Mag body seems more resiliant, albeit at a small weight penalty (I am not a super weight weenie so I don't mind, I am more into how the part functions).