Yes, you need keyword.enabled set to false otherwise Firefox will still search even though you have a different search box :(.
In Firefox, it is also possible to set keyword.enabled to false and still search explicitly in the url bar via the keyword search mechanism (they overloaded the terminology a bit :/, the one if you right click on a search box and select "add a keyword for this search"). I've been thinking of trying to just use DDG style ! keywords via the url bar (and s for a default search to make it easier to type, maybe single letters would be easiest in general) rather than a search box. OTOH, the keyword search (the second type :/) seems neglected and I wouldn't be surprised to see it disappear at some point.
In Firefox, it is also possible to set keyword.enabled to false and still search explicitly in the url bar via the keyword search mechanism (they overloaded the terminology a bit :/, the one if you right click on a search box and select "add a keyword for this search"). I've been thinking of trying to just use DDG style ! keywords via the url bar (and s for a default search to make it easier to type, maybe single letters would be easiest in general) rather than a search box. OTOH, the keyword search (the second type :/) seems neglected and I wouldn't be surprised to see it disappear at some point.