i've used base malt in that same age range with no problem, but i do find that the flavor doesn't 'pop' like fresh grain.
if the grain smells nice, it's probably good to use. if it smells musty or stale so will the beer.
sparging is a little wonky with these things as well, at least in comparison to a dedicated mash tun. this thread goes over it quite well:
the recipe was likely created with a mash effeciency of ~75%. if your particular system will yield lower than that, as many all in one systems do (they're essentially biab), then you need to adjust for that by using more grain to reach your expected gravity.
The all in one systems are generally lower in mash efficiency, at least without really dialing in the sparge process. You can account for this in planning ny adding a bit of extra grain or dme in the boil.
There's a maple bacon porter and a mango/mole wit in my brew queue. perhaps i'll get crazy and push it further into the weird stuff realm, but i've got a long list of beers i wanna get brewed soon as it is.
and similar to day trippr, i miss those "aha" moments. reading an obscure blog post after ah hour of google searching rabbit holes and find an 'oooooh, so that's how they do that; i need to try it asap!' type info.
I really don't miss being inexperienced enough to not be able to distinguish between people who had genuine understanding and experience and those that were just regurgitating things that they had read and assumed were true.
I call my octoberfest ales "OKTO VERATA NYmhhnmm"
Its an octoberfest, maybe not in every single little tiny way, but basically it is, yeah.
a low, rumbling howl in the distance preceds volleys of thunder...