Hey euanemblin! Another fellow JG53 member
Essentially the DBW and SAS buttons flight models are a hybrid, derived from what our admin team here consider the 'best' flight models out of Ultr@pack, HSFX, Histomod, AAA UI and stock (plus some of our own). Whilst realism is what we aim for, we've also chosen flight models which fly and 'feel right' in game. There are sometimes limitations to the IL-2 flight engine and also sometimes limited real world info on the flight envelop of aircraft. Where those cases exist, we've tended to go with the 'best fit' and 'feels right' approach. Also remember SAS has always aimed to cater to the offline campaign and coop players, so FM consistency hasn't been such a strenuous requirement as it is with online packs and you may also find some of them have extra features e.g. opening canopies.
So our FMs aren't necessarily better than others, but in terms of compatibility for mods, ours are pretty comprehensive and will allow you to use any mod with DBW, SAS Mod Act and HSFX6
BUT it might not guarantee online compatibility, that's all