This 1791 Gunleather Optic Ready Open Top Multi-Fit Belt Holster is not compatible with the Springfield Echelon. I would recommend the DeSantis Thumb Break Scabbard OWB Belt Holster made specifically for the Echelon, which can be found by using the link below:
https://www.opticsplanet.com/desantis-thumb-break-scabbard-owb-belt-holsters.html
Yes, the 1791 Gunleather Optic Ready BH 2.4 Belt Holster will accommodate your PSA 5.7 Rock with a red dot optic equipped.
Yes, the 1791 Gunleather Optic Ready BH 2.4 Belt Holster is compatible with your 92X RDO compact and allow for you to have an optic installed.
The 1791 Gunleather Optic Ready BH 2.4 Belt Holster will not fit a Springfield Hellcat. We do carry many other options compatible with the Springfield Hellcat that you can find using the following link:
https://www.opticsplanet.com/s/holster?_iv_availability=in-stock&_iv_gridSize=240&_iv_parent-gun-make=springfield-armory&_iv_parent-gun-model=springfield-armory-hellcat
The 1791 Gunleather Optic Ready BH 2.4 Belt Holster will not fit a Taurus G3. I would recommend the DeSantis Mini Slide Leather Belt Holster that will accommodate your G3 with a red dot. You can find it using the following link:
https://www.opticsplanet.com/desantis-mini-slide-holster.html?_iv_gun-model=taurus-g3c
The 1791 Gunleather Optic Ready BH 2.4 Belt Holster is designed for full frame handguns with barrels ranging from 4"-5". It will not fit your XDM Elite. Using the link below, you can find the compatible holsters we carry for your XDM.
https://www.opticsplanet.com/s/springfield-xdm-elite?_iv_categories=holsters&_iv_parent-barrel-length=range-3-3-dot-99-in
Suppresser height sites most likely will not fit.
They are very universal, you shouldn't have an issue but we cannot guarantee it will work.