I thought I'd share a major announcement to the industry. For those who are looking to do full mods or upgrade an existing door operator, Wittur now offers a "One size fits all" design called SGV (AMD Model similar). It is designed to adapt to existing hall door pick up rollers, requiring only a change of cabin door equipment. It is capable of adapting to OTIS 6940 (not NG, HPLIM, 7661), GAL, MAC, Miami Elevator/TKE, KONE AMD (Which is essentially the same operator), Westinghouse (except retiring cam models). If for any reason the operator doesn't support your type of door pickups, you can just order the AMD style rollers and clutch. These operators are also available for completely now applications. AMD/SGV style clutch/rollers are selected as default.

Another option is the GAL MONXT. This product is similar to the Wittur product and is better suited for lower overhead clearance; however, if used on a mod, you will have to replace your hall pickup rollers. It's not one size fits all like the former.

Both of these door operators are European style, which typically have more safety features, such as cabin door interlock (no gate switch, which could get purposefully or inadvertently activated at the wrong time, and no "less reliable" door restrictor, which could become a snag hazard, in the case of the angle-iron variety, or purposefully jammed in the unlocked position by a tech, in the case of the GAL/MAC?Miami Elevator variety, or even worse jam in the locked position with dead battery, in the case of Adams HatchLatch). With interlock, door cannot be moved ajar. Also, no need for ugly sheet metal between landings on glass jobs. The clutch engages independently from the door movement, reducing a snag hazard due to misaligned doors. The doors can't be split apart at floor level causing door lock faults due to the clutch design.
The design is non-proprietary. Parts are available from multiple sources (KONE, TKE/Vertical Express, and Wittur) Link: https://verticalxpress.com/media/download_files/component_manuals/ld_16_udo_mod.pdf

Flyer: https://www.gal.com/wp-content/uploads/2020/06/GAL_MONXT.pdf
Installation: https://www.gal.com/wp-content/uploads/2021/01/MONXT-Operator-Installation-Manual-DELTA.pdf

Whatever you do, I wouldn't recommend harmonic op. They are just too outdated and don't offer all the safety features of Euro style operators. Installation is more time consuming because they need more complex mechanical adjustments. GAL is the only company that still makes em. They need to stop, lol. Especially in today's day and age. See first paragraph to learn more. Another downside to harmonic ops is that some makes and models can become self locking (operator can move the door but door can't move operator). This can cause problems during entrapment where the only way to get the door open is to climb on top and spin the infamous wheels. This can be dangerous is you have long floor runs (i.e. train stations). This is what cause the entrapment at the WTC on 9/11. With linear operators, they are never self-locking. They can be easily opened from the floor or cab top. The amount of force needed is always uniform throughout the entire door cycle, to manually open the door. Plus, if the power is cut, the clutch is spring-loaded. If elevator is at floor during an entrapment, all that needs to be done from the outside is cut the juice and then manually open the door (no key or lock picking). If door arm bolts get loose or detached, they could fall on someone. With a belt operator, if the belt breaks, it will just loose traction and stop. Another bad thing is when they are used on glass door installs (propped up on pedestals. This creates trip hazards for workers and adds installation costs for taller hoistway.

If you really wanna see how dangerous a gate sw is. Check out this vid. Be glad it was equipped with DLM: https://www.youtube.com/watch?v=AEOkZDBCDiw