The RX is an older model and comes with the Romeo 1 while the RXP comes with the Romeo 1 Pro, hence the P
I have a Compact RX and a Full size RX and they are both great handguns. Going to come down to whether you want the newer Romeo 1 Pro...
My only experience is with the Romeo 1, I am sure someone with experience with both can compare and contrast them.

 

P320 RX:

P320 RXP:

OK, here is the deal Airborne 82nd,

At the end of the day what do you ultimately want to end up with?
The RXP comes with a X-Series Grip Module./ RX does not
The RXP comes with Sigs Flat Trigger / RX Does Not
The RXP comes with the X-ray3 Suppressor Night Sights / RX does not

I purchased a Compact RX in 2017
Since then I have turned it into a RXP without the Romeo 1 Pro:

• I first added a X-Compact Grip but I now have a Wilson Combat Carry MS Grip.
• I added a Keres Dynamics Flat Trigger

Both the Grip and the Trigger cost roughly $125.00
I purchased my RX for $750.00 + $125.00 = $875.00 for what I wanted.
To add the Manual Safety was about $175.00 but that does not really count in this discussion because neither comes with a MS..
I'm just sayin'

I do not have X-Ray3 Sights instead I have Sig Suppressor Night Sights
I only had to rely on the Iron Sights once when the Controls on my original Romeo 1 started to be intermittent.
Sig replaced my Romeo 1 with a Brand New V5 Romeo 1 and I have not had a issue with it.
SO...
Obviously you can leave alone or build out either the RX or RXP as you prefer.
SO..after you decide to build or not to build and costs thereof..
You Compare the Romeo 1 vs the Romeo 1 Pro
Here are a few links comparing the R1 & R1 Pro below..
However if you search the web you can find a lot of information about both Romeo's.

Review: SIG Romeo1 Pro

https://www.opticsplanet.com/questions/questions-sig-sauer-romeo1pro-1x30mm-red-dot-sight/7612d516-
ca94-11e9-8711-06cb6c26348e.html

Review of the SIG Romeo1 Pro

SO
In the end do your homework....Look at them both if you get a chance...Hold them both
In my opinion (and everyone has one) I do not think that you will go wrong with either one.
BUT
If it was me today making the choice and I could afford the RXP ...I would purchase the RXP.
If not I would get a RX and build it out to my liking.
Sig offers the same Warranty for the R1 as the R1 Pro..
If You have an issue with either...
Well with Sig's excellent Support You really do not have a issue..If you get my drift.
I had a new Romeo 1 in less than 2 weeks mounted to my slide!
Ka-Bang..that's how Sig rolls!

But that's just my opinion.
FYI..
If you prefer the original P320 Compact and not the X-Series there is a Compact RXP.
It has a curved Trigger, 3.9" barrel and Contrast Sights instead of the X-Ray3 Night Sights.
I'm not sure why Sig did not upgrade the sights on the Compact.
P320 RXP Compact

 

OK, here is the deal Airborne 82nd,

At the end of the day what do you ultimately want to end up with?
The RXP comes with a X-Series Grip Module./ RX does not
The RXP comes with Sigs Flat Trigger / RX Does Not
The RXP comes with the X-ray3 Suppressor Night Sights / RX does not

I'm not saying you are wrong, but how come the sig website shows RXP with curved trigger and non X-series grip?

Those are on the RXP X

P320 RXP Full-Size

The next level of striker-fired modularity with a slide-mounted reflex optic. NO RECEIPTS NO WARRANTY CARDS FULLY-TRANSFERABLE FOREVER SIG SAUER® Infinite Guarantee™

www.sigsauer.com

P320 RXP XFull-Size

Full size XSeries performance with the latest reflex optic technology.

www.sigsauer.com

 

Good post above, but the RX does come with X-Ray 3 sights, or at least all 3 of mine did. Might not be quite suppressor height, but they are very usable with the stock optic. I bought the X frame for one of mine, and went back to the stock one. I like the more rounded grip, just fits my hands better.

The reason Sig went to the P optic is because the Army demanded a Delta Point Pro footprint on the M17/M18 guns. So it left Sig in a position where they didn't make an optic that would fit a gun they were producing. So they changed their proprietary footprint slightly on the R1 and called it a "pro" version. Same basic optic as far as I can tell.

 

The reason Sig went to the P optic is because the Army demanded a Delta Point Pro footprint on the M17/M18 guns. So it left Sig in a position where they didn't make an optic that would fit a gun they were producing. So they changed their proprietary footprint slightly on the R1 and called it a "pro" version. Same basic optic as far as I can tell.

Do you have an estimated timeline on this footprint change? That way I can look up my "born on" dates and determine the footprint. I have both the RX and RXP slide with optics but also have an unfired M18 I purchased recently that is September 2020 so I would imagine that is Romeo1 Pro AND DPP compatible. The other 320 is in .357 with no plate (swap out the slides). The reason for my inquiry is I am strongly considering the DPP after seeing it in real time. Very clear glass and dot.

 

The main advantage of the R1P is that it is the new standard SIG mounting footprint - and as such will take the new Romeo 2 and Deltapoint, likely others trying to get in the SIG market. It is the footprint SIG will mostly likely build optics for in the near future. I have both. The R1P seems more robust. There are companies that can convert a slide from R1 to R1P. You won't go wrong either way. Cost difference? That's a wash after a few range sessions with actual ammo.

 

My rxp had standard suppressor sights, standard grip module, and standard trigger.

Sent from my LM-Q720 using Tapatalk