Welcome! I would send off an oil sample to get it tested to see how the oil is holding up over that period of time. Places like blackstone labs, etc can do it. If nothing else, it will give you a piece of mind!
You'll get more out of a custom tuned ECM over something like a harness module that Banks offers. As always, that depends on the tuner itself but usually the custom tuned ECM will be smoother and more powerful.