We use GoldMine and our marketing/cr people love it. It's very slim usage though, like 5 or 6 concurrent logins, though we are tracking tens of thousands of customers and sales leads. For what we do it suits our purpose, and our minimal load has never been an issue, nor are we putting any demand on a relatively weak application server that hosts it (it's an old P-III 800 that still runs like a champ).
From my perspective it's very easy to backup/restore/administer if anything goes screwy, and I have never experienced any complaints regarding the GoldMine system in regards to file contention/file locking issues. We've got around 6 or 7 years worth of sales data in it and the entire db directory footprint is only around 70 Mb too.