If a Catholic faction, yes, Mercenary Crossbowmen are great indeed. But let me tell you something about Reiters... Oh. My. God.

I absolutely love them, after I discovered they shoot when charging. The combined effect of a cavalry charge and a pistol volley seems impossible to bear by opponents. Usually they rout immediately after impact, and it works against most enemies if charged in flank or back (especially, of course, against light troops).

It's now my first HRE campaign and I trained a couple of Reiters just for fun, not really needing at that point any uber-late-period units to win any battle anymore.

I didn't know about that charge-shoot combo at the beginning, so I just deployed my Reiters in the flank of some Moors spear militia, planning to soft them up with pistol fire. The incredible short range was really disappointing (the previous campaign was as Turks, imagine using static Reiters after Janisary Musketeers).

Then, bored, I redeployed my Reiters and tried to use them as usual cavalry - charge, retreat, charge again. WOW! they charged shooting at point-blank on target and all those (surviving) pesky militias routed!

I'm pretty amazed. Use a high-valour general with 3/4 Reiters and you won't lose anything anymore...