I got a few Burris fastfire 3s. Shot it on a pistol today and have one on an ar pistol. They can be found $150-200. Check academy. Oh make Sure there is a red dot in the box before you leave... ask me how I know!
+1 on the fastfire if you’re talking about that type of dot. Hard to beat that for the money. The Vortex would be my next choice, for a few dollars more tho.
If you have an X-Five with a Romeo1, it has a Romeo1 footprint and won’t fit other optics. You will need an adapter plate for whatever optic you choose.
IMO, the Fastfire series isn’t worth buying. From my experience it is one of the cheaper made optics. Vortex has a good warranty, but their MRDS are not much better than the Romeo1 that you’re sending back. The RomeoZero posted above won’t fit your slide either. It has the RMS-c footprint.
The Holosun 407C and 507C are excellent optics for the price. Both will fit your slide with an adapter plate.
If you want to spend more money, you can have the slide modified for a Delta Point Pro or use an adapter for a Trijicon SRO or RMR.
The issue you will find is that if your X-Five is cut for the Romeo1, it won't fit some optics plates or the DPP like newer Romeo1 Pro cut slides will. If you have a slide for a DPP/Romeo1 Pro footprint, then you have other options.
I got a few Burris fastfire 3s. Shot it on a pistol today and have one on an ar pistol. They can be found $150-200. Check academy. Oh make Sure there is a red dot in the box before you leave... ask me how I know!