Shedhand,
The thermal protection is the main thing you need for protecting your motor. A 3 phase CB in an enclosure can do that job no worries, although $92 for a start/stop box is pretty competitive when you factor in what your own time is worth.
With rotary switches, well, depending on which one you used, it may not be rated for motor start (and particularly) stop function. Electric motors chuck out a high voltage spike when the current to them is suddenly interrupted, which if the contacts on the switch are not designed with consideration for, leads to premature death of the switch. It's less a safety thing and more a "it'll probably break sooner than you'd like" sort of thing. The DOL box in the link above has a contactor (big a*** relay), which snaps open far faster than a rotary switch will, which minimises damage from on/off cycles. For most larger equipment, it's far preferable to having switches which directly control on/off. It also normally deactivates on loss of mains, which is another important safety feature. Also, once you've got a control box, it's normally trivial to add emergency stop buttons on more convenient locations on the saw.
In the mean time, you should be right to use the saw, but the idea will be that you need to listen to your machine. If it bogs down, pull the work back and give it a break at no load speed before pushing on. If it stalls, stop pushing and/or power immediately. All the commonsense stuff that comes with being the owner of a machine that you plan on being the owner for for a long time.
It also helps your motor if you periodically remove it from the machine and clean it out. Being choked by sawdust is probably a bigger cause of death of woodworking machinery motors than anything else and the most easily avoidable.
You're probably already aware of all of this (to some degree or another), but I'd say it's pointless not using your machine for the sake of a switch. Change your habits to match the design of the machine - it'll make sure that it lasts longer even after you upgrade it later on.