This was confusing until the second or third time I saw the post; I've never had a toaster with slots, only convection ovens with toaster functionality but also the ability to make bacon. Though for the latter, you'd definitely want some foil or something involved.
They're probably not as cheap, but I'd definitely recommend a convection toaster over a regular one to almost anyone.
My current convection oven is pretty sizable due to having a multitude of functions, so I'm not denying that what you've said is certainly a possibility; but most I've ever had have been been very basic and only a little bit larger than a slot based toaster. Honestly, in most of my homes, I could have gotten rid of my large oven and replaced it with a convection oven - that would save a lot of space!
I've lived in my current house for around eighteen months and only used the full sized oven once (when my wife wanted to make more cookies than would fit in the smaller one). Of course the appliance you should get is the one that fits your use case, but I've never regretted getting a convection oven.