No serving staff below the board/CEO level has 'firm' F class tickets in BA. Why should you be any different. My 'firm' F tickets are downgraded if my family travels with me operating the flight. The become 'waitlisted'. Often commercial ops will temporary embargo the F cabin to allow for commercial upgrades leading to the F priority staff travel ticket holders being waitlisted until <24 hrs prior to departure.
ST is not a 'right' it is a concession as such it is BA's concession to play with, as stated above BASSA found this out the hard way.
In my experience the Gate Crew, Cabin Crew and Flight Crew will ALL do their very best to get ST passengers to most comfy seat they can when the opportunity arises. In all honesty the 'booked seat' element is primarily for catering and I will try and get ST travellers as far up the front as I possibly can. But then you don't like the product so no loss there then.
As to the baggage issues, BA doesn't differentiate between ST passengers and commercial passengers when it comes to processing baggage claims. They can't, the claim process is a legal process. In my experience again, and obviously the experience of posters above, on the very few occasions my bag has been delayed a poilitely worded letter with receipts for obvious essentials has had my claim settled promptly. Perhaps a 'bull in a china shop' approach doesn't garner the same results? I don't know but I'm just guessing.
As far as 'checking' loads on both the ST and the Retired Travel sections of the intranet goes they never, ever, reflect the actual commercial load of the aircraft. They do show an estimated commercial overbook position. Hence it may show free seats and onload priorities for staff but those seats might not actually be there in the event of an industry standard overbook policy. The only way to get an accurate figure, as 4468 was alluding to, is through FICO.
But as you seem to be an upstanding, high level member with all of the alliances around the world then all of this is irrelevant isn't it.
Enjoy Finnair.