your best bet is to go with the specialized hardrock sport.
i do 4-6 foot drop offs on a hardtail, so yes a hardtail is fine. and i no a lot of people on these forums probably do a lot more then that on a hardtail.

Go with the specialized hardrock sport, then later down the road wen u get into the sport more, look on e-bay or look around for a last years model fork and get a good deal.

either that or save up a lil more money and get a lil better bike.
trek seems to be more expensive, but i like the feel of their bikes a lot. not too much of a difference in the bikes your talking about.

i answered your questions, but this is what i think you should do.
save up $50 and get a trek 4300, or get the hardrock sport if you really want it.
a year later swap out the fork if u feel the need to.