For money-smart sailors who don't race and don't want to spend the extra coin for UHMWPE, a good intermediate step is polyester parallel strand core with braided polyester cover. Gleistein makes this, others probably too. It has no constructive stretch and less elasticity than braid-on-braid.
Would use this for Genoa and Main halyards, possibly also for outhaul. For the rest (sheets, control lines, etc.) polyester braid-on-braid is fine. Original sizes as fitted by Bavaria are sensible and do not normally need adjusting. If you do want to adjust for some reason, make sure the new size is compatible with your sheaves, blocks and rope clutches (the size range is usually written on them).