Ok, Johny, seeing as you're familiar with the ins and outs of Samedan, i'll make good: here's my thinking...
With a thin but solid layer at 2500 AAL, and 10k visibility below that, you can fly up or down the valley maintaining more than 7000ft of altitude, which is a minimum not only to keep the locals happy, but also to keep a reasonable distance from cables and most hang gliders and such, and most importantly, with about 150 knots (good maneuvering speed for a G5 in intermediate configuration) at 7000ft, a 180 deg turn is possible in ANY part of the Engadin valley, PROVIDED there are no "hanging" clouds on the side of the valley.
Local procedures recommend a straight in approach from either Zernez or Maloya, depending on RWY. If the hole in the layer is not over those points, but over the field, as happens quite often, the need arises to fly up or down the valley, and do a 180 turn for final. Not so problematic on the Maloya side. On the Zernez side, i prefer to take the long way, and go pas the village of Zernez to the south branch of the valley for a wider turn.
My minimum requirements, then, to start such a procedure:
1. the hole in the cloud layer is big enough for me to see slantwise ALL THE WAY to the point where i need to make the turn, BEFORE I commit to descend below the layer.
2. The elevation of the layer is such that i can maintain more than 7000ft for the whole procedure.
3. No hanging clouds, precipitation, haze or strong/gusty winds.
In addition, following points are part of the flight preparation:
1. Phone call to the Samedan airport before we take off, to get their take on the weather, the traffic situation, VFR activities, etc..
2. Thorough briefing in the cockpit regarding go/no-go factors, procedures etc.., also BEFORE getting near LSZS
3. Early radio contact with Samedan, to reconfirm latest conditions, as well as talk with the other trafic. (by the way, on wednesday, we had a chat with an Swiss Air Force helicopter, a Pilatus 12 and a Challenger crew on scene before even cancelling our IFR)
4. In addition to the normal weather/notam briefing, a good long look at the military and other shooting activities (KOSIF), the Swiss VFR chart as well as the Swiss Glider chart (cables...) needs to be taken.
I won't even get into the passenger and company issues related to this kind of operation, as the differ so much case to case and company to company. But that's really where it all starts, because if there is any pressure from that side, the game gets very dangerous.
The point i'm trying to make is that sufficient information, discipline and common sense are safety factors all the time, and more so with airports like Samedan, Gstaad, or Aspen. I would much rather have a crew prepare thoroughly every time, then go near the operational limit, than impose some sort of company limit, which will then be applied without further thought.
I'm sure You have excellent reasons to apply Your own personal limits to operation in LSZS, influenced by Your experience, Your airplane and it's performance, Your company and Your passengers. There is nothing to say against a prudent attitude, ever. So good on You for not letting the company put pressure on You.
I have my own set of rules and guidelines, they are a result of experience and attitude, and I don't really like to be labelled suicidal by a fellow professional, even with a question mark...