5 gal is too small for anything but extract batch with topping water going into the fermenter on top of the wort. I have two of them for some silly reason. Until I got my 10 gal pot I'd split my boil between the 2 pots and then combine for chilling (still a good strategy if you are a stove top brewer btw) but PITA trying to chill 5 gal of wort in a 5 gal pot with immersion chiller...
I do still use my 5 gal pots almost every brew day so not a terrible investment, but do get at least one 8 or 10 gal pot for boil and chilling (+1 on the bayou classic, mine is 10.5 gal, seems to be perfect size for 5-6 gal batches).
Note it is really worth debating whether to just get a 15 gal pot to enable 10 gal batches. When I bought my 10 gal I was sure I wouldn't want to mess with 10 gal batches but not so sure now. Could be a bigger pot in my future, but if so I'm thinking my current pot should still be decent size for heating strike water. Right now I'm telling myself that I could probably do a 9 gal batch in my current system, starting with 8 gal in the 10 gal pot and 4 gal in the 5 gal pot and combining for chilling...
Having some extra pots is pretty handy on brew day. I use my 5 gal pots to condition grain, collect filtered water, collect second runnings, even split my wort between 2 or 3 to get it boiling allowing me to use multiple burners on the stove top.
Soon I'll get a burner and move outside. Soon as it warms up anyway.