Tinfoils also get too large to keep in a school or schoaling situation in your tank. I think with an aggresive type fish like a convict, your loaches would simply be bullied into becoming reclusive, which they tend to be anyways. I do love loaches though and if it was my tank, I might still try to keep some.
How big are your fish? I ask because I am keeping some tiger barbs in my cichlid tank, which is working out well. Tiger barbs get larger than most might think (about three inches, and very 'roundish' type fish, like a tinfoil barb) and would most likely be too big for your other fish to eat if you place them all in the tank while they are still young.
They are also good because they are constantly active and their 'nipping' habit is usually nipped in the butt when they are in a tank full of fish that will fight back! I have 8 in my tank and until recently, I had three kennyi and a johanni in the tank with them. Never had a problem with fins and my cichlids couldnt catch the tiger barbs. It kept my tank very active and relatively aggressionless (although attempts at aggression do happen, but are never very successful.