System choices

Right now, I'm brewing beer via BIAB (that's "brew in a bag") mashing in a 15-gallon kettle. I'm doing 5 gallon batches and there isn't much that's ideal about the system except that BIAB is much, much (much) easier to clean up than having a dedicated mash/lauter tun (that's an MLT, btw).  The kettle is a holdover from a larger system I used to brew 10-12 gallon batches, but most of that system is gone (given away before a big move) and it was actually a bit broader and shorter than was ideal, even for a 10-gallon batch, so it's positively wide for a 5-gallon batch. Not the end of the world, but I end up with higher boil-off rates than are ideal, and I've had one or two beers with what seem like excessive melanoidin (burned toast) character that may not entirely be the result of the grain bill.

I'm very excited to be making beer again, and I've fallen in love with the time efficiency of a 5-gallon BIAB batch. That said, I've not been thrilled with the low efficiencies (low 50%ish) I've gotten doing BIAB batches, so I'd like to move back to having an MLT, and batch sparging. I get that a lot of people like mashing in a kettle so they can goose the temps, but in my experience with a cooler-based MLT (using one of those fancy keeps-ice-for-five-days coolers), losing temp was never an issue in the first place. Step mashing is fun in a kettle-based MLT, but why not go full-German and do a decoction if you want to step mash?

So, I'm at a crossroads where I want to expand back into multi-vessel brewing, but I'm not sure where to go.  Do I double down on BIAB by getting a grain mill and a nicer bag, spending my energy on chasing down efficiency with tighter milling and control?  Do I go back to a variation on my old system, but with a smaller cooler, given that I plan to stick with 5-gallon batches?  Use my current kettle as the hot liquor tank on a full-on three-vessel system? Do I stick with only 5-gallon batches, or size equipment to give me the option for 10-gallon batches?  Bite the bullet and get another boil kettle more appropriate to brewing? 

I think it really boils down to the two paths I see folks taking most:

First and most-common (or most-commonly bragged about in online forums) is the brewer who steadily expands his brewing setup through acquisition of ever larger and shiner kettles until they've replaced their living room with a single-tier all-electric HERMS system, brewing 1bbl batches fermented in a row of stainless-steel conicals sited where the couch used to be. These guys spend more money than I'd spend on a car on their gear, but they do have systems that let them brew easily (my back was always in a bad way after a big batch...there's something to having a pump over using buckets when you're moving 100 lbs of near-boiling fluid).

Second, are the guys like Don Osborn or Denny Conn, who brew constantly over the decades using the same mash tun and turkey-fryer kettle, winning awards for beers fermented in plastic buckets in the coldest closets available.  These guys still expand their systems (I see DonO is using a stainless kettle these days), but tend to spend most of their time/money on ingredients and actually brewing. 

I think I like the second path, especially if there's room there for an erlenmyer flask or two, but it wouldn't hurt to take note from the first path and choose items that make a brew day easier on the body where it counts.

I hope no one was expecting an answer to this tonight.