Musketeer, Bolt Action and Anglian are almost identical.
GB usually is a tad bigger, but specifically the WWI Woodbines are not. They match quite well with all three above mentioned ranges. Incidentally the (small) Foundry WWII range is also a very good match.
Great War Miniatures is another matter. Figures are taller but still acceptable , even in the same unit. The weapons however are much bigger and heftier.
I like GWM and have all of their Late War Germans, but I would keep them in separate units.
Crusader is a bit chunkier than Bolt Action, Anglian and Musketeer but will also mix quite well.