At this moment you can get by without FSUIPC as long as you select the proper FSX version be it SP2 or acceleration and the configurator confirms that the aircraft was modified for your version. In the earliest version all it did was configure some gauges and the aircraft.cfg so it be compatible for both SP2 and Acceleration. In upcoming releases it will be absolutely necessary. Being in stock mode is not bad at all, it's considered our "middle of the road" setup. With FSUIPC installed the configurator can change many things including thrust, fuel flow, wing span/area, actual loadout weights and a few more things, all relative to the actual aircraft model.
My advice is to get the freeware FSUIPC and try it out, read through manual and you will see how much of a "Swiss Army Knife" it really is. The freeware version will work just fine.
Edit - You have version 1.00, as long as you get a confirmation that the files where modified all you would have to do without FSUIPC is to re-select the aircraft. In V1.00 you only needed to run the configurator once.