Today's plan is to put one agent on Sugar, as an upgrade from paper. Absolutely, SugarCRM is overkill.
Maybe thousands, or at the most, tens of thousands of records. Should we hit a performance wall I can always remove older records. While I don't anticipate more than 10k records for many years, that is a potential pitfall, but, I think, not a worrisome one. Now that I see how Sugar works a bit, I'm more comfortable. I'm not a PHP guy, but the rest of the stack is right in my comfort zone.
So far, the only table I've customized is Opportunities. For myself, I like the capabilities of Sugar, but, yes, the business case isn't really there. This is more about going from paper (if you can believe it) to a database as quickly as possible. If it creates a hassle down the road, I'll cross that bridge when I get to it.
I already demo'ed Sugar and have the go ahead, so am somewhat committed. I specifically selected Sugar because it does integrate with ViciBox, which is the long term goal. Ultimately the company wants to take the hosted Asterisk PBX in house, but that's in the far, far future.
If necessary I can always export from the database to CSV and then import to...whatever ViciBox uses, but I'm sure there's a better way.
I like the sound of millions of leads, of course