I have a 3 in 1 Smithy 3 in 1 model CB 1220 XL.
Fortunately, I didn't get the memo that said you can't make anything will them...
IMO having worked on larger machines, it is a decent lathe and an okay milling machine.
The work envelope is what it is... The mill spindle is too darn close to the column and I can only mill a little less than 8" travel, so you have to pick your battles. The round column can be a PIA, but having used it a couple years now, I just think ahead when doing setups, which is always a good idea, right?
It is really a 4 in 1: lathe, drill press, vertical milling machine and horizontal milling machine! I often use the lathe spindle with a fly cutter or mount a cutter in an arbor between the centers to bore a long straight hole in work mounted on the cross slide/carriage!
It does seem like whenever it is set up as a milling machine, I need a lathe and vice versa. But, I can change it from one to the other in minutes! Of course you have to dial in your vise, etc.
The tooling is the same as single purpose machines. Because the spindle at it's lowest is still pretty far from the table, one possible needed extra is 2 x 4 x 6 blocks or one of those riser blocks to put under your smaller vises, toolmakers block etc. I like the work up where you don't have to have the spindle all the way extended.
I for one, will never look down on 3 in 1s. If you have limited space and or budget, and you are not building a full size locomotive, you can't beat them. If you find a good deal on one, I think it is a great way to get your feet wet as a hobby machinist!
I would like to get a better mill and maybe a better lathe one day, but if I do, I think I'll keep this machine, too!