New Purchase, Need Advice, Considering S55 or RTiA5, Need Surrounds

Been reading through this forum for a bit now, and I need the collective brain to knife through the noise in mine. First, the noise:

My sig has my setup, but will add that this is for movies only. I have vintage speakers that I've been upgrading over time, and understand warm vs bright sounding setups. My Onkyo AVR I use for music is rather sparkly, but the Daytona's I have on calm it down a bit. With the EQ, I balance it all out even more. My EMF's are warm, as is my Sony AVR, so I'm looking for a bit more high-punch there. Normally I listen to the speakers first, but I do not have any local place that demos Polk.

Last year I remodeled my theater (room is 13'Wx26'Lx8'H) and installed two 70-RT's in the ceiling for Atmos, which pair very nicely with my center. My intent was to go with RTiA3's for the rear channels and the A5's for front L/R to match everything, but over the last few months, the RTi line is hard to find. The A5's I can still get in black, but A3's are long gone for reasonable prices. I can however find A1's for surrounds. I was intending to get the surrounds first (replacing the weakest-sounding of my set currently) and then either the fronts or my sub. So, I'm presented with the following choices:

• Write-off the RTi line, find that the Signature line will pair well (sonically, not visually) with my center and ceilings, and buy an S15 or S20 for surrounds and continue with my upgrade timeline.
• Purchase the A5's while they're still available (at a considerable price break over an S55 mind you) and revel in the nice aesthetic match once re-stain my cherry center to black. (sigh...)

I recognize the general feeling that the A5's are brighter than the Sigs, but this set will not be doing music, only movies. As stated earlier, I want more punch at the high-end for movies, but I know that both the Sigs and RTi's will do that. The surrounds though:

If I stay with the RTi line, I'll need to buy both quickly, and "settle" for the A1's or go on a patient hunt for A3's. If I see that the Sigs are just the better way to go, then I swallow that my center will simply not match visually, and figure out whether to get the S15 or S20.

So, to the collective: Are the A1 surrounds up to the task, which I take to be at the audio-level of the S15 relatively speaking, or do I bail on that and go for the S20 for my surrounds? The answers to this will focus on one of the choices above and give me my roadmap.

Thanks to all.