According to
http://www.therabbithouse.com/diet/rabbit-food-comparison.asp the GA for Supreme Fibrafirst:
30% fiber, 14% protein, 3.5% fat, 0.8% calcium, 0.4% phosphorus, 2:1 Ca
ratio (phosphorus basically cancels out calcium)
The fact that something contains alfalfa shouldn't matter if the overall protein and calcium content of the pellets is on par with what you'd find in a food that's only got timothy. Also, when you see timothy first and alfalfa second, that doesn't necessarily mean much - the hay breakdown could be 55% timothy/45% alfalfa or it could be 95% timothy/5% alfalfa.
Think of it this way - bunnies aren't supposed to eat a lot of sugar, yet we're allowed to give them fruit (which is almost all sugar) as long as their fruit intake is within the appropriate limit for their weight. In the same way, alfalfa
can be ok in pellets as long as the formula is balanced to where the pellets aren't providing more protein and calcium than they should be. Alfalfa pellets get a bad rap because the vast majority of alfalfa-based pellets are NOT appropriately balanced... but from what I've seen, the "no alfalfa pellets for adults" rule is outdated.
People say "no alfalfa-based pellets" because there was a time - not long ago at all - when alfalfa-based pellets that fit the nutritional needs of house rabbits simply didn't exist. Times have been changing, though - alfalfa-based pellets are starting to evolve; a small handful of alfalfa-based foods are now balanced to have a GA appropriate for adults.
UK vets pretty much set the curve - the science of house rabbit care is more advanced there than it is here; I'm very fortunate that my vet in San Antonio keeps up with what the UK vets are doing instead of waiting for new trends in rabbit care to slowly become widely-practiced in the US.
When I got my rabbits and we discussed diet, he actually recommended an adult diet of unlimited grass hay, 1/8-1/4c alfalfa-based pellets per day (for 3-4 lb rabbits) and lots of leafy green veggies. He said conventional wisdom in the US is that adults should get timothy-based pellets and grass hay but that in the UK, most vets had switched to recommending an alfalfa-based pellet w/grass hay because emerging research points towards an alfalfa-based pellet actually being better (so long as pellets are appropriately limited and grass hay is the majority of the rabbit's diet.
I showed him the GA and ingredients for Sherwood Forest M/S
(which is alfalfa based but has a GA that fits what we look for in a timothy pellet - it's actually one of the eight foods highlighted on the chart in the first link I gave as being "ideal" based on the GA fitting *all* guidelines) and he agreed that it was in line with his recommendations. In fact, of the top eight pellet brands, four of them have alfalfa as the first or second ingredient (three of those also have a significant amount of timothy).