Large content database considerations and optimization techniques?

One of my customer is looking forward to upload their file share content to SharePoint Server 2010. 

The file share is consisting of 2 TB of data where each TB of data will reside in a separate site collection. 

I'm aware that the content database size can be extended from 200 GB to 4TB after installing Service Pack 1. After much research, I understood there are couple of options to store such massive amounts of files without harming the content database size.

1) RBS provider or FILESTREAM provider

2) Separate data into multiple content databases (implies having multiple site collections each containing in its own content database)

I see that going with option 1 we still have to deal with additional infrastructure cost, maintenance and planning of backup and restore operations. However 50% of the files are > 1MB, do you recommend to go with option 1?

Option 2 requires maintaining a lot of site collections (up to 200 GB) and may not be ideal in terms of planning perspective. What do you recommend if in future, the size goes beyond 200 GB per site collection? Exporting to a new content database may be another option but we may loose metadata information and the client will be quite reluctant on it. 

Still little confused which option to go with. Please advice.

Other main concern is:

1) How do we optimize such large lists because it's obvious that we would be crossing more than 5000 list threshold limit. What is the maximum limit that it can be changed to? Even after changing will it still affect the performance.

2) What about the search? Even after going with option 1, it still needs to index lot of documents. How to optimize on search?

3) Any other performance killers that I need to be aware of and how it can be re mediated? 

Please advice and this is a time constraint.

Much appreciated,

Vamsi

Vamsi Munagala