Up to you, but it honestly really isn't that much of an issue and I'd trust a simple properly crimped joint (which is easily visually inspected with a simple tool) a heck of a lot more than a welded one that is impossible to see what the inside looks like... um, did I put the right amount of flux on? did I know to use the 1/2 of solder to 1/2 of pipe trick?

As far as insurance companies... I bought an old place... I'm finding all sorts of stuff that isn't up to code (hidden electrical boxes, in the floor!, with wire nuts and not even twisted together wire and not even grounded properly)... I'm bringing it up to code, with modern products... in a court of law, it is going to be hard for them to argue against me.

Depends on what you're doing. I've done quite a bit of DIY, and much of it is probably better than if I hired someone for the simple fact I care, and I'm not trying to do it as fast as possible.