The development of grapevine varieties combining powdery mildew (Erysiphe necator) resistance with acceptable wine quality represents an important goal for sustainable viticulture. This study evaluated the oenological potential of five advanced breeding lines carrying Run1 or Run1Ren1 resistance loci, developed through marker-assisted selection to achieve 99.2–99.6% Vitis vinifera genome content. Genotypes were assessed under Chilean conditions during the 2024–2025 seasons, analyzing disease resistance, berry characteristics, and wine chemical parameters. All resistant genotypes exhibited complete powdery mildew resistance (OIV scores 9) without fungicide applications. Wine analyses showed pH 3.4–3.9, titratable acidity 3.7–7.8 g/L, and total phenolics 229.2–1356.1 mg GAE/L, values within ranges reported in the literature for commercial wines. Two genotypes evaluated across both seasons showed different patterns of year-to-year variation, with AJ-T2 showing 4.7% variation in anthocyanin content, while AJ-T6 exhibited greater variation in phenolic parameters. HPLC analysis revealed anthocyanin profiles dominated by malvidin-3-glucoside without diglucoside forms, consistent with V. vinifera patterns. These preliminary results from single-plant evaluations suggest that marker-assisted breeding may contribute to developing disease-resistant varieties with wine chemical parameters within commercial ranges, though multi-plant trials with appropriate controls are essential for validation.