Count me as a huge fan of BIAB. Using BIAB and getting over the "standard" 5 gallon batch size have enabled me to brew more often and spontaneously.
I started brewing in 2000 and quickly went from extract to all grain. I used a three vessel gravity-driven system: HLT, Mash tun, and boil kettle with propane burner. Some great beers were made but the set up took a while and the brew day was long. There was no way to leave a brew set up in place outside so every brew day involved pulling out multiple coolers, a ladder for gravity fed sparge, and the time to tend to an open flame from the propane burner. I am not a young man so hauling rubbermaid coolers with sparge water onto a ladder was not a pleasant task. Also many times all the prep for brew day were ruined by horrible weather since the propane burner required outdoor use.
The goals were 1. Brew indoors and 2. Make brewing more spontaneous and less labor intensive. Don't get me wrong, I loved making the beer , but getting a brew day in required a long period of dedicated time to tend an open flame, good weather, and a good back. It got to the point I only brewed three times in four years (young children make it difficult to have the dedicated time!)
The solution: I now use BIAB with an electric turkey fryer. I started doing this about 5 years ago and for me it works perfectly. The Masterbuilt/Cajun Injector electric turkey fryer uses a standard outlet and the heating element is not very powerful. I added some insulation and have done batches from 2.5 to 5 gallons with no/problems. The fryer comes/with a stainless steel basket which is perfect for keeping keeping the grain bag off the heating element. I usually do do batches of 2.5 to 4 gallon size which work well with the power of the heating element and the size of the fryer kettle.
For me this is perfect. Electric: no tending an open flame and I brew in my garage- even with the door closed when the weather is horrible. BIAB: I fill the kettle one gallon at a time once for all the water requirements - no ladders! - and dont have to haul anythng until I drain into the fermenter and move it to the fermenting frig. Most importantly - no open flame to worry about. Even during the boil , no worry of boilover with a smaller batch, I do other things around the house. I just keep the timer with me to remind me when to add hops, whirlfloc etc.
Vive BIAB and the smaller batch!
I have brewed four times since the new year and three of those days the weather was horrible - snow or rain. Using my old system I would have only brewed once outdoors. Yes the batches were smaller but I got two 2.5g and two 4g batches done instead of one 5g on the outdoor propane system.
Also by doing smaller batches I have brewed beers up 1.068 starting gravity. If you stop thinking every batch has to be 5 gallons you can do quite a bit.
I LOVE BIAB