Some thoughts on the maths of the 10% discount voucher:-
If a batch 1 order (pair of miners) was 1.50 BTc then the voucher will be worth 0.15 BTc
So a future order for Batch 4? will have a starting price of (pair of miners) 1.35 BTc
Deduct the market reduction Bitmain have been applying of at least(pair of miners) 0.05 BTc = 1.30 BTc maximum (copied from the Batch 3 price)
Then you arrive at 1.30 Btc less the voucher of 0.15 BTc
This puts a Batch4? (pair of miners) at a net cost of 1.15 BTc
By the time the backlog of orders are cleared, then another market reduction will be needed. (another 0.05 BTc)
By the 20th of this month we should expect to pay no more than 1.10 BTc for a pair of Batch4? miners.
Does anyone agree with my figures?
So I am not sure of this 10% discount voucher you are talking about but if you are referring to the expected coupon from purchasing a previous batch I am going to have to disagree with you a bit. First off there has to date only been a 0.025 Btc drop in price between batches, therefore batch four will more than likely cost 1.425 for the pair of S3s. Now as for the discount or coupon we, hopefully, will receive for purchasing batch 1 or 2 S3s, I wouldn't bet on it being for more S3s. When I purchased my S1s I got coupons for a S2, while I did hear of people getting coupons for S1s I never did. With that being said if Bitmain still has stock on S2s I would not be surprised to see a coupon for those until stock runs out and then perhaps a coupon for an S2 upgrade or maybe the S4(if one ever gets released). Also as the S3 is going to be Bitmain's bread and butter for a bit I wouldn't expect them discount them too much too rapidly. That being said I would expect a batch 4 release price of .71-ish or .7 per unit. Anyways those are my thoughts and if I missed something about the 10% voucher in a previous post please disregard my rambling.
Edit:
Okay so I just got the 10% voucher notice for my batch 1 order. Yes there will be a 10% credit towards a future S3 order or a 7.77% discount on my existing order. With that when batch 4(or if 3 ever reopens) we will probably be looking at a pair of discounted S3s for probably a number of 1.28 btc.