One aspect that has not being discussed is the energy density - in my application I have very limited space for LiFePo4 battery - for the space I can place 210-280ah battery, while only 100ah Battleborn. This was deal breaker for me for Battleborn.
I agree. Energy Density--which can further be broken down into 'volumetric energy density' (i.e. how many units of energy per liter) and 'gravimetric energy density' (i.e. how many units of energy per KG)--is certainly an important factor in many situations. Its something I have been thinking about more lately. I suspect for most of us volumetric energy density is more of a concern than gravimetric, but both are important in some contexts (and neither are important in other contexts).
A related factor is the ability to customize a DIY battery pack to the space you have available whereas a drop-in usually comes in only one form-factor, maybe two or three at most.
In practice I think its quite difficult and sometimes misleading to compare volumetric energy density between drop-ins and raw cells difficult (or even between different types of raw cells). Its a hard comparison to accurately make before you have actually constructed or at least designed your pack. Because raw cells on their own (particularly large form factor aluminum cells) are not equivalent to a battery. BMS + whatever external protection/compression/casing you use should be factored in. If you design it reasonably well
you can avoid adding too much extra volume (a simple aluminum plate and threaded rod enclosure could add almost no volume beyond the BMS, but from what I've seen a lot of the homebrew DIY enclosures or commodity battery boxes do add a decent bit of bulk to the finished product, and depending on the application more space does need to be devoted to protecting the cells.
Rereading my comment, I'm worried it may come across as disagreeing, which is not my intent. I certainly agree, if volumetric density is the primary consideration a smartly designed pack made of aluminum cased cells is a sensible route to take.
Here is an interesting (to me) comparison of sizes of various raw cells (in 4s packs) compared to a battleborn.
From left to right: (00) Coke Can for scale
(0) Wine Bottle for scale
(1) EVE 105Ah (dark red),
(2) Frey/Fortune 100Ah (White/Grey),
(3) CALB CA 100Ah (Turquoise),
(4) Lishen 272Ah (Yellow),
(5) CATL 202Ah (Blue),
(6) CALB SE 200Ah (Green),
(7) Battleborn 100Ah (Red)
All measurements were taken from datasheets, and are not 100% comparable as some are just rectangular cell dimensions, some include the height of the terminal, and some include the height of the stud. Ideally all would be the total height, but this should give a ballpark at least. As you noted the Battleborn does not compare favorably at all in terms of energy per liter.