i hope you try the climax..a late version , not the original
i have a couple sound versions and they are , imho, nicer than the shay, as they are rather diminutive.
they are great locos.
FWIW the shays are LARGE, and heavy. Climaxs are not so heavy.
both shay and climax will handle R1. The drive rods into the shay trucks dont like these, however, as the truck pivot is right at teh edge of retaining the tip of the drive rod in the truck gear housing.
if youre in doubt about which shay might be safe, the 3 truck shays all came with metal trucks.
i cant help you with more detail.
the earliest version 1, 2 truck 36 ton, which is what i purchased when first released. This version only came with a diamond stack, and not the later versions that came with multiple stacks (straight, cabbage, rushton). It is one to avoid, unless it has replacement trucks, ( i have one, it broke in about 30 minutes , after opening it new , running light. ( i have no idea if the ebay one is the same or version 2 or later)
I fully reworked my original trucks, with the shoddy plastic, gears, and ball bearing pick up brushes, and they still were abhorrent. I hated that loco, (and bachmann), until i bought new trucks. then i loved it. i hated shelling out $60 back then (???1992 ish???) for what should have been included. (it was about what i would have paid in shipping it back under warranty...)
back in pre Flu prices the metal trucks were/ and are now about $260 US.
they are much harder to find in the past year or so., even at that price, they are a worthwhile addition if the loco has the old trucks.
if you find a shay, as greg mentions, it is really important to get one with the later metal trucks, and, for that matter, all its parts, as parts are almost impossible to find now.
you should also know, if this is your first bachmann foray, the plastic is rather brittle styrene, they are not weather worthy one jot, and, bits and pieces are fiddly and can easily fall off, including micro screws, or break, seemingly without reason.
the pilot steps sit very low too. The can catch on things like track power connectors if not carefully attached, switch machines, etc. if they do, they willbreak.
Extra care is needed in handling, and, very important, all bachmann stuff, but especially the shays and climaxs need regular lubrication. bachmann smoke units ...thats an oxymoron. they smoke profusely at 18 volts, for a short time, provided the reservoir doesnt leak like a seive. if run dry at much over 5 volts, they will self destruct
i avoid heavy loads. while the shay has tremendous pull, the gears on the axels have been known to strip and spin. the first versions simply broke in half. you also need to never allow anything to get into either climax or shay running gears, like leaf bits, tiny twigs or pine needles, etc.
you should also be aware that fitting lgb hook and loops to either loco can be challenging. and, as for knuckles, bachmann sits at a different height than lgb.
i wouldnt avoid them, as they are a sight to behold and to run. But if something breaks, that might be the end of it.
they are nothing like LGB in terms of robustness. OTOH, they look like a model train, and a magnificent one at that.
so, bear this in mind if you plan this loco to be a work horse. i cannot attest to longevity, as i run all of my B mann stuff very sparingly and carefully after my first shay. i now have 2 C19s, (amazing fidelity, huge) , 2 sound climaxes, and 2 of the last version 2-6-0s, both magnificent, great runners, one 2 truck shay and one 3 truck shay, and still need great care in handling. to my knowledge, they dont like wet. But i live in Colorado, so i imagine on your pond side, you might find a better source in this regard.