I haven't seen any difference in using points vs. vouchers, except for some weird rules (ie - using points upgrades also the short haul feeder, using vouchers doesn't. Or you can use vouchers to upgrade a reward booking, but not points)

But if you really feel that you have more success with points, the solution is easy - use points, and when the u/g clears, call CS and ask them to return the points and take one of your vouchers.