Which indicator would be the most appropriate for titrating aqueous ethylamine, ${\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{NH}}_2$ , with nitric acid, ${\mathrm{HNO}}_3$?

The graph below shows the titration curve of $25{\mathrm{cm}}^3$ of $0.100 \mathrm{mol} {\mathrm{dm}}^{-3}$ of hydrochloric acid with sodium hydroxide, of $0.100 \mathrm{mol} {\mathrm{dm}}^{-3}$concentration. The indicator methyl orange was used to determine the equivalence point. Methyl orange has a pH range of $3.1–4.4$.

If the hydrochloric acid was replaced by ethanoic acid of the same volume and concentration, which property of the titration would remain the same?