had an ai606 on my first cinq, good cat 1 alarm, it really depends what you want the alarm to do and what features, in terms of going off when someone breaks in and immobiliser then yeh they are good, its just adding extras can be a bit fiddly.
If you want the number of a decent local installer (northampton) give me a pm and ill give u his number, he fits, toad, clifford, autowatch, laserline and is insurance approved and v.s.i.b certified