[34C]

Snip away if all you need are track power input and motor output, all those are on the six pins.

A thought, might you someday want to use the decoder for another purpose in some as yet unknown future? If so trim the wires short enough to fit inside the loco, and put shrink on insulation on the bare ends. Easier connecting to wire ends than soldering onto tiny tinned patches on a crowded decoder board. Ask me how I know this...

 

[34C]

...The only thing future wise that I can think of would be the fitting of a stay alive and that would be only if the Loco needs one for uninterrupted running , do any of these wires need to remain for that ? .

Unlikely. The common ground connection is on one of the six pins if memory serves, and the other connection is probably somewhere on the decoder board, there may be a solder pad if you are lucky! (I'd suggest researching that before purchase, and I see you have just spotted another 'trap'!)

Then again, you may find as I do that 'stay alive' is never required. I was greatly attracted to this feature when first looking at DCC (now twenty years ago!) and bought the Lenz UPS unit to try with the then very new Gold decoders. Oh boy did it work, but how often did I want to put a sheet of paper on the tracks and see the loco continue to run under full control? On a properly wired, live crossing point, all metal wheeled stock layout, in regular operation, it was simply unnecessary.

The constant DCC track power at whatever 'full voltage' is set (I have my system set to deliver 15V at the motor terminals) 'gets through', operation is near completely reliable without stay alive assistance, and it gets better. When I see the occasional loss of reliability, which is the moment when a loco 'stutters' slightly at dead slow, that is diagnostic of some dirt having arrived on the loco wheels or railhead. Immediate action to clean up keeps the layout clean. I wouldn't want that 'stutter' masked by a stay alive, it's a clear signal that a gob of dirt has fallen off a loco onto the rail and should be dealt with.

 

[34C]

Both the common ground and the decoder positive are NOT on the six pins....

Thanks, I'll try and remember that; you can tell I am unfamiliar with six pin decoders can't you?

....I disagree on Stay-Alives, they transform the running quality of smaller models in 2mm, 4mm and 7mm scales. These are models with all-wheels picking up reliably, carefully laid track with live frogs, etc.. And, I've had a fair few skeptics saying "not necessary" who come round to ordering retro-fits in their locos having seen what locos do. Its not about running over a sheet of A4 - a pointless party piece. Its about fractions of a second of hesitancy.

The UPS, party piece aside, didn't discernably improve running on the locos I tried it on, equally smooth with or without.

Now here's the aspect where you will likely disagree, I actively want that 'occasional fraction of a second of hesitancy', as it is a clear signal of significant track dirt.

I routinely run a track drag for rail cleaning and that deals with the constant low level railhead dirt deposition very well: but the one thing I haven't been able to eliminate is the occasional 'blob' of greasy filth falling off a loco mechanism and landing on the rails, and cleaning it up before multiple wheel passes 'spread it around' is my priority. And it is the locos that detect these events, by that occasional fraction of a second of hesitancy. That's a signal I don't want suppressed by an efficient stay alive like the Lenz UPS. This is something like a once a month event, and I operate the layout near daily, it doesn't detract from the pleasure of operation.