My experience is fairly similar to yours FF. I'm about 11 months in and 93 roasts. I've done less mods than you, just a standard Heatsnob. I'm finally getting close to finishing my bean cooler, but like you I've been cooling outside the machine for most of the time I've had it. It's definitely the way to do it.
After experimenting with getting really involved with manual intervention I've reverted to letting the machine do its thing for the most part. The learning has been what batch size and profile to use. 250g is my most successful and most common, but I often do 300-350g batches as well. I almost always go into manual mode about 2/3-3/4 of the way through the roast, mostly so I can use the higher drum speed around first crack. I generally keep things as simple as possible.
My next mod will be a BT probe, I think this is almost a necessity. Just trying to decide if I drill another hole in the side to fit it or not. One thing for sure, it's an enjoyable machine to use that produces excellent results and I don't regret getting it for a second.