Sorry, I read through the version notes and found the reason why Alpha option is off for now.

When using "/color x y z a" the last (alpha) does not do anything to gridlines, so I simply assume it's not taken into account or maybe it can't be done?
Simply wondering as I thought it would be great to just run a low-er visibility more ghost-y grid at ALL times.

You can use alpha < 1 if you want to if you set the colour explicitly in the options. That change was made so the lines wouldn't disappear if you changed your player colour to "0 0 0 0" but still wanted lines. The line colour setting (mod settings > player settings) doesn't force alpha to 1 though.

Your colour can't be full brightness though for Factorio to render it transparently. So use something like "0.5 0 0 0.5" instead of "1 0 0 0.5" if you want green transparent lines. Just how Factorio does it.

oh ok, I hadnt realized. thank you for reply.