I am conflicted about the helix…
I tried the grade around the room rather than in a helix and it just wouldn’t work (the room’s too small). The helix is a grade of 3% but does stick out alot…
The thing that is good about a helix is that it is simple to operate. A train elevator is much harder and having used a variety of fiddle yards/sector plates etc, they can be very manual and more prone to errors, derailments, general problems. They also need to be quite long to fit on a train which can make them unwieldy.
My feel is that the helix follows the KISS philosophy and so is probably safer, even if it is not ideal.