I got a pile of batteries in one envelope, not the best way to ship batteries, even when they are shrink wrapped. Efest have changed their packing.
1A is handled very well, but even 3A is possible with these IMR cells.
Thse IMR batteries handles a high load for their size.
Conclusion
These IMR batteries have very good performance at high loads, but the capacity is, of course, not that high.
At the current time I can only rate them acceptable, because Efest is a new company, and the batteries is not from one of the big brands.
A few low current chargers for 10440s: XTAR XP1 (250mA), Micro Lipo mcp73831 (100mA / 500mA, default 100mA), LipoNano (100mA / 500mA, default 500mA). Lipo nano / mcp73831 test. You can even connect an AAA battery holder to the micro lipo without soldering (twist & tape).
With efest10440 250mA is 0.81C, 150mA is 0.49C. LiMn might be able to tolerate more but don’t want to risk losing any capacity from charging too quick.