I have used the simple system one, it was good and solid. Had a horse that was very greedy so ate all of it in one go, still took about 15-20 mins. They certainly have to work to eat it compared to a sloppy simple system feed, just remember that it is the same stuff as in there grass nuts so does really count towards their feed weight.
We used Simple Systems for a while and switched to feedmark. I think the pack we have at the moment is Equimark. Whatever is available really.
We use them as an alternative fibre source - so if a horse is kept in he can have a choice of hay net or block etc. 1 block is equivalent to approximately 1/2 net of hay. But you do have to look at the nutritional info. The Simple Systems one particularly is very high energy.
One caution though - we don't give them to our choke prone appie as he seems to inhale it more than he chews it. We could soak it into slop if we had to though.
I've fed Simple Systems, I use them as an occasional treat when stabled. She likes the Lucibrix but isn't too fussed with the Meadowbrix. Though the Meadowbrix are infinitely more palatable if soaked in boiling water overnight and fed mushy in a bucket.
I've used Simple systems but now using Halley's. Fat appaloosa can annihilate a block in 10 mins if they are left on the floor but a bit longer if they are in a small net. She will also dunk in her water bucket to soften them up.
Hairy cart horse can take all night to finish one. He particularly like the Lucie bricks.
I have used both kinds as an occasional treat as my pony wasn't that bothered with them unless I soaked them. Ended up giving some away to other horses on the yard who also preferred them wet. When dry a lot of it got mixed in with the shavings bed and so got wasted. I think I would only use them now if my pony was stabled for long periods just to add some variety to her day!
Thanks everyone, I intend to use them as a boredom breaker on the days when the weather is dire, and the horses have to stay in, something different for them to do.
Not the two that you mentioned but I use the following:
Equiblox, these are the cheapest I have found at under £1 each, the 'Original' ones contain hay and alfalfa and the 'high fibre' ones contain straw as well, they are dull but last a while because they are very compact
Agrobs, these are more expensive at around the £1.30 each mark but smell amazing and the ponies are definitely more keen on these, they are much softer though so don't last as long
Both can be soaked in a bucket of water to get a chaffy meal which takes a while to eat and the Agrobs ones also break down in to wonderful dry chaff
Personally I don't like them, I brought one as a treat and watching my horse eat it seemed hard work, I just don't like the amount off force he was having to use with his jaws to try and bite into it.
I found the Simple System blocks much harder than Feedmark's but big horse has to have either type in a net or she chokes, that's because she is a greedy oik! I wouldn't bother soaking as I might as well just feed chaff. They are used as an occasional extra, not on a regular basis. Mini Shetlands can hoover through one each in 10 minutes, greedy little monsters!