If you have the sunny garden space available then a 5 to 7 gallon pot with holes in the sides , planted in the garden for the season (as soon as you would plant your tomatoes), would perform even better than a SIP in my experience. I have very little of that kind of space so my SIPs ,especially the 25 gallon ,are for me the next best thing.
With the in ground pot you would have the smaller size portability for storing for the Winter as well as the full rooting access to good garden soil for the season. This could also give you a greater length of time they would be fine without being watered if gone on vacation etc...
I love my SIPs , but realize my figs would grow even better if planted in the ground for the season , if I had a access to a sunny garden site.
Last season I had a Hardy Hartford in a 5 gallon pot , planted in very poor gravely soil at a friends house, and with occasional liquid organic feeding it out grew almost everything else and yielded very well.
If you go with SIPs , for me the production is much better in the few 7 to 8 gallon SIPs compared to the 5 gallon bucket SIPs. I just can't find that size pot very readily or cheaply , so the 5 gallon buckets are what I use for now.