Multi-DB: Add field to New DB or 4096

Hi,
This is my first stupid question (to this site). I searched for answers to this, but must admit that I am a WPMU newbie fighting for a clue and may have overlooked answers or common sense.

Question: should I simply create a single database of a few text fields that each blog will have a record in or attempt to add text fields to the 4096 DB?

What are the performance tradeoffs? [Right now, few blogs (alpha testing), but I plan to have 1000+]
Or does the insanity of modifying and possibly breaking 4096 DB outweigh any possible performance?

Andrew and James at incSub installed 4096 DB for me. So, I'm trying not to mess that up since it works.

[mylocalcause.com is a blogsite where users raise funds and awareness for their favorite non-profit or cause.] I'm looking to add a new text fields "cause name" and "cause address" to document the name and address of each blog's designated cause for commissions to be sent.

Right now, I'm just using the existing $blogdescription field to capture this information.
For functionality, want users to be able to select from causes already entered from other users.

Thanks in advance for your patience.

Best,
Kevin