After talking with the guys at Dean Safe, I decided on the SF series from AMSEC because it exactly fit my list of needs. The SF7240 was the biggest unit I could fit in my space and still meet my budget. Everything in the safe is nicely finished and the interior fit is very flexible - the premium door panel is fantastic!
Configuration is very easy, and I plan on adding some MOLLE panels for additional options. Three metal shelf covers are included, along with a couple of thick standard shelves. The covers are there to close up a pass-through for longer rifles and shotguns. The fabric inside is an industrial upholstery with a tight weave.
I'm impressed with the door balance and friction, and the upgraded mechanical lock is smooth and solid. The bolts are smooth and secure, and the handle has no wobble or rattle to it (a little play is necessary; I'm talking about the slop you get on some low-quality safes - there is none of that here). It only takes a little pressure on the door to seal up due to the gasket.
I installed a mylar back and LED strips for visibility, which required completing the electrical pass-through (about 20m total effort start to finish).
After all of this, however, the reason I chose this safe was because of the customer service. Any questions I had were answered directly and accurately, without any marketing spiel or buzz words, and I did not feel rushed at all. This was an extremely easy decision, and I'm very happy with the results.