After working on open source software since 5/6 year and implementation of the same at NIT Rourkela and various library, i would like to suggest use open source solution with in-house staff only if?
1. If you have dedicated library professional who are willing to give their personal time to library after office hour i.e. who works for library at home too.
2. If Library managers personally willing to give time to library and company to team at-least.
3. If staff are active member/always following open source email groups/social site groups and various discussion forums.
4. If you bother about value of money/public money.
5. If you have capability to take risk/challenge as good administrator.
6. If you have passion to do something new and extra ordinary.
7. If you are ready to spent many sleepless nights during implementation.
8. If your main technical person have primary objective to give priority to project rather than their own priority so he/she can’t left project in middle.
9. If you are willing to work as per international standards.
10. If you want to get better recognition among subject fraternity and may be many IF?
by 
I agree with your points. These are challenges always come with OSS.
One thing may be added that is:
If your authorities agreed to implement OSS.