As long as you keep the joint clearances tight, silver will be plenty good and it is much easier to control than brass.

I've never liked flux-coated rods, but if you like them it's easy enough to make your own as you need them. Just heat the bare rod and stick it in some powdered flux. Be aware that the powder fluxes and those used for coated rods tend to be hard to remove afterward. By far the best brass flux I've used is the "Type B" paste flux from the Gasflux company. Works like a champ and comes right off with only hot water and a stiff brush.

For silver I use the "Type U" paste flux, also from Gasflux. Silver fluxes tend to be much more acrid than brass fluxes, so be sure you have some ventilation.