You mentioned several uses for a power supply, each of which does better with certain features.
Around the Christmas tree needs are fairly simple - don't need momentum, braking, meters, etc.
For a DC test track, I find meters and a non-pulse power supply are quite helpful. A DC test track will NOT serve as a programming track for DCC unless you install a fool-proof way to switch the test track to DCC. My test track is for tuning locomotives and breaking them in - and for that DC is better than DCC. But I do the tuning and break-in before adding the decoder - which I confess I actually never do because I don't use DCC yet.
For accessories: Tortoise (and other stall motor type) switch machines and the turntable motor generally require DC. Twin coil switch machines and lights can use either DC or AC. The current draw of your turntable motor, and the amount of lights will drive your power requirements, but you'll need at least 12VA in reserve to "snap" twin coil switch machines, even though it's only a momentary load.
Bottom line is that the advanced features (momentum, braking) of the more powerful Tech 2, 3, 4s don't do much for you in your particular uses. If your power requirements fit within the specs of a Tech 2, 3, or 4, then it's a reasonable solution. Probably a better possiblity is 2 separate solutions - each tailored to it's use. A low end Tech 2, 3, or 4 (used Tech 2 or 3 is as good as a new Tech 4) is fine for around the Christmas tree, and if equipped with meters, great for the test track. The easiest and cheapest solution for a moderate-to-large-sized accessory load is a suitable toy train transformer with a full wave rectifier added to provide DC where required. With the addition of meters, the transformer/rectifier setup will also work for the test track, but would not look pretty enough for most Christmas trees.
Hope this helps.
yours in transforming