Cordless vs. Corded Tools
It's all about power vs. convenience. A cordless drill is convenient when there isn't a power outlet nearby, but it may not be able to hold enough power to sustain the use of a large bit. New cordless tool innovations are allowing some larger tools to become nearly as powerful as their plugged in cousins. For an application such as drilling a large hole with a hole cutter, opt for a corded drill.
One inconvenience of a corded tool is the possibility of the cord becoming damaged. A bent plug or a reciprocating saw that accidentally gets cut along with the wood can wipe out the tool. Some reciprocating saws have a removable cord that can be replaced.
Another advantage of cordless tools is the ability to purchase several tools at once without blowing a budget. Some cordless tools now come in kits that provide several tools with one or two batteries at a relatively low price.
There are times when a cordless router needs to be used, like when working on a new house that hasn't been wired for electricity. There's also danger of the cord getting cut with this tool. When working on a profile on a long board, the cord could be stretched to its limit, ruining the profile.
In the case of circular saws, it all comes down to power and capacity. A cordless circular saw has a smaller blade than a corded saw. Also, it just doesn't have the power to cut through a thick board. When cutting some chunky pieces of wood, find an outlet nearby. When working in the yard or on a jobsite, the cordless version may be what's needed.