I am using Joomla, K2 and JomSocial on my site. Component works good with Joomla. The JomSocial re-write engine is excellent so i have not used the component on JomSocial. There are many problems with K2, such as Pagination, tags, search etc. It does not work well at all. There is no customer support, so i highly do not recommend purchasing this component. Go for the free version, Pro does not give any benefits at all.