A little background... I have in the past, helped a red team that specialised in automotive theft (for those unaquinted with the term, I was paid to test security systems by driving/riding vehicles away & hiding them from tracking)....
living in an area that has a bad rep for motorcycle theft
Firstly, welcome to the forum. Since you replied to an old thread, I'll assume you read it - all very good points.
Next, you live in Belfast (according to profile). I work in Liverpool, so the risk profile is probably the same. Although I park in a secure car park in the city, a Ducati rider that used to park next to me took his bike to the dentist in Liverpool - came out, it wasn't there.
So, the aim of the game is simple, make your bike less attractive to steal than the one you park next to, and you're golden.
Luckily, you bought an ST, old enough to be overlooked, and the parts market would immediately be flagged on this forum and a few others if thieves started chopping them. Good start. Plus, the scooter & scrambler gangs would drop an ST getting it off the side stand.
Given you're not a high profile target, avoid the electronics (which, FWIW, aren't worth the money regardless of risk profile IMHO). You don't need a tracker, if an ST or its parts pop up in Ireland, they stand out a mile.
My advice, would be to get a large chain & padlock - something from Oxford probably, and look to spend around 120Euro or thereabouts. Use it properly, chain the bike (back wheel) to something heavy/immoveable and don't leave any chain trailing on the floor.
Job jobbed. I wouldn't waste money on a disc lock, it'll only throw you off the bike the day you forget it's there.