Although I've little experience of ferrite rods on LF receive I did wind my 
600uH 500kHz ATU loading coil for my 5w transverter on one.  With just a 5m top 
loaded vertical it worked well without saturation problems when  sitting on the 
bedroom table. At QRP it is less lossy as less wire is needed. 

People have successfully engineered (single turn I think) ferrite rods as TX 
antennas for 10MHz QRPp WSPR. Somewhere I have some information on this. As 
long as saturation is avoided there is some mileage for HF TX applications in 
very compact QRP stations. 

Worth some experiments on LF receive Stefan. 

73s
Roger G3XBM

Via my iPod Touch 4g 2.4GHz handheld.