The 5211 can be modified to switch more reliable.
The capacitor C5 of 220uF can be enlarged – but not too big though, else it will take to long to charge it. I chose another 220uF/25V. Also if it bacame much bigger it would not fit inside the 5211 box. Just solder it parallel to the existing capasitor – positive to positive and negative to negative.
P.S The schematic is of the old 5211 with descrete components. The new are with more SMD components and I have heard its slightly different (but not much – an extra diode and such)