I use the StomaGenie with every wafer change. It gives me a hassle-free way to clean around my stoma without worrying about stool coming out. I have never used the SecurPress because it would not be convenient for me. I use a barrier ring around my stoma and a moldable wafer. The StomaGenie should be at least 1/8" larger than your stoma. To use the SecurPress: (1) while the StomaGenie is over my stoma, I have to slide the barrier ring down to the bottom of the StomaGenie; (2) I have to mold my wafer opening and then slide the wafer down the StomaGenie above the barrier ring; (3) slide the SecurPress down the StomaGenie on top of the wafer and press down; (4) lift the StomaGenie along with the SecurPress off your stoma.
If you have a tape boundary around your wafer, you need to still remove it. Also, the barrier ring is not hugging your stoma since it is probably at least 3/16" away from having to slide down the StomaGenie.
If you aren't using a barrier ring or a moldable barrier, things are a lot simpler. You just place the StomaGenie over the stoma, slide your wafer over the StomaGenie, and slide the SecurPress over the StomaGenie and push the SecurPress down on your skin. You still need to remove the tape boundary from the wafer if you have it. Since the wafer slides down over the StomaGenie, your wafer opening has to be slightly larger.
The SecurPress is designed to work with the StomaGenie, but if you are not concerned with stool collection while you change your wafer, I don't see why you couldn't just use the SecurPress alone to press down on your wafer once you have it attached to your skin.