First off--stoploss traps can't be beat.They have put thousands of muskrats on my stretchers.I use them when trapping shallow water areas,and in areas where a muskrats may tangle the trap in vegetation(which in my area is most places).I ,use a bit of extension chain with extra swivels,to allow the caught rat to reach deeper water.If this doesn't happen,your stoploss spring holds your rat,till your arrival.
The old wives tail,of the stoploss spring throwing out trapped animals, is just that--an old wives tail.There is no way the stoploss spring can beat the closure of the main jaws.Now if a rat is toenail caught,the spring may pop them out of the trap,but you weren't going to hold them with that type of catch anyway.
I catch many coon and beaver in my rat sets(with #1 stoploss) the largest beaver held in one,was 53 pounds.Many of the coon have been over 30 pounds.If your trap is in good condition ,and you use a sufficient staking system,you will hold coon.
4 years ago,I worked with Bill Duke on redesigning their stoploss trap.Every design change I asked for,was put into this trap.I think you can ask anyone that has used the new Duke stoploss,and they will tell you it is a fine trap.
Tom