The model 6 uses the same internals as the model 10 both having twin reciprocating pistons but different trigger parts.
The 6m has the barrel sleeve from the 10 but 6g does not.
Early guns with the original seals that revert will either have failed by now & been replaced or will fail very soon.
Guns with seals made after about 1985 will probably be okay even today, they are that reliable & probably out last the springs which have been known to go for twenty plus years with constant use, springs are very high quality.
The model 6`s are easier to strip than the model 10 but neither are rocket science but you will need a spring compressor.
Sometimes the cog covers can be a bit tricky to remove without damage but other than that easy!
Reliability is excellent.