I dont think I can agree with that position Vincenzo. I think the total force structure needs to be considered, for both sides, as the best approximation of numbers involved.
I concede that the the numbers of Heavy Bombers (Lancasters, Halifax, Stirling, for the most part), generally did not exceed 2000 aircraft, in 1943, for example, the average readines rate for the heavies during the battle for berlin were 1179 Heavies, but a total of 1740 aircraft in total. By the logic you are applying, we need to ignore the risks, and losses suffered by the mediums and Lights supporting the Heavies (Wellingtons, Mosquitoes etc). We should also ignore the efforts of the the supporting arms, the recon elements, the intruder groups, the spoofers, the Night Fighter forces and the like. I dont get that, since the Night Fighter forces also possessed numbers of support elements. I think the most valid comparison is to compare force to force and make a simple comparison
The argument to support your position really falls away when you look later in the war. By July 1944, the average readyh Heavy Bomber Strength of the Command had risen to 1609 aircraft. As far as I know the numbers of big raids had not changed greatly since the Battle Of Berlin, however the sortie rate had soared from around 5000 per month to well over 20000 per month. So, with a heavy bomber force of only 1.36 times bigger than 1943, the RAF was mounting 4.4 times as many sorties. I do know from my reading that the RAF did roughly double sortie rates for individual aircraft (better maintenance, less flak damage I suspect, given that the estimated flak expenditure per kill rose from 3000 rounds per kill in '43 to 16000 rounds per kill in 1944 ) and also improved operational readiness rates in 1944, but it would be very hard to argue that the heavy bomber aircraft alone, even with their increased sortie and readiness rates, and increased numbers, could account completely, or even predominantly for that increase in overall sortie rate. to me ther is only one other possible explanation....the RAF was sending other aircraft over Germany, in addition to the Heavies. I know that the operations of the Mosquito Groups increased dramatically, and I am not aware of any great reduction in Wellington operations (they did decrease as a percentage of the total effort, but not as a raw number). (However Blenheim frontline operations all but disappeared) My guesstimate is that sortie rates across the board roughly doubled in 1944. That, coupled with the 136% expansion of the heavy bomber force means that the Heavies were responsible 55% of the total 20000 monthly sortie rate (speaking very roughly). The remainder must be attributed to the other elements of the command.
I also checked some additional sources concerning the Night Fighter strengths. It seems that most sources quote an average operational strength in 1944 of 800 aircraft, with an average additional strength of 350 for the wild sau formations. In 1943, the average NJG strength was about 650 aircraft.
So even though we can argue semantics all day, about the details of numbers, exactly what you want to include in the force structure to determine casualty rates and the like, the basic numbers underpinning this whole combat relationship has not changed. relatively, it was more dangerous for the Night Fighters than it was for the bombers, and relatively, the NJG groups were suffering a higher attrition rate than Bomber Command. You cant avoid that conclusion, if you look at the numbers subjectively