I have run G-Zero foam blocks in my 5 gallon IMS tanks for 5 years.
Absolutely worth it. Last forever. No break down or clogging of filters. No loss in volume and no sloshing!
2013 Ducati Hypermotard SP, 2011 Husaberg FE570S, 2011 BMW S1000RR, 2010 BMW F800GS
2007 Husqvarna TE610 , 2003 KTM 525 MXC