Be VERY careful when buying "generic" drugs when it comes to horses. I know of at least one that died this way.
However, with that said, I think if you can get omprazole at a less expensive route, then do it. It has been shown in other peer reviewed articles - I can find 'em if you'd like - that keeping the stomach acid to lower levels will help performance horses. This includes adding forages such as alfalfa that are high in calcium - look at the calcium levels in mylanta (HIGH!!!) - calcium is what helps regulate/control the stomach acid which irritates the ulcers.
There are different ways to treat many things, the important point is to treat what is diagnosed correctly by a veterinarian - in an appropriate manner as well.
I have been down this dang ulcer road for the last 4 years - do your treatment and then I highly recommend succeed (I get the powder granuels) and it has made a big difference - I have tried several things trying to keep this under control- and this stuff has been awesome been on ot about 8 months now and my boy just looks awesome and is eating on the road- ( which was a huge issue with us) he has not been yo-yoing any more with weight -its a lttle pricey but it actually works
i bought 2 tides of the ulcer guard.. because i think my gelding has ulcers.. 99.9% sure. vet will be out tuesday though. but I'm just looking for something to give him to keep them from coming back. so would that product be good? or is it supposed to be fed as the whole treatment??