Being a dh person i should were armour but im realy not an armour person, when it comes to dh and djn i feel i cant move as freely as id like.
i do own a 661 prop preesure suit, elbow guards, shinnies, tld t bones, fox neoprene knee pads, full face, skate lid (mucken around, djs etc) and roadie helmet.(longer rides)
For dh i wear the tld tbones, not to short not to long.
when it comes to just messing around and djn i found because i have week kness if i hit the deck without any kind of protection on id be on the ground in pain for at least half an hour before being able to even stand up. Hence i bought the neoprenes, no to heavy not to light, acts more like a brace then anything.
I havnt worn shinnies in a looooooooog time i find them uncomfortable and as i have very skinny legs i could never get a pair that fitted appropriatly in length and width. I only wear the pressure suit when im on a super rocky track (so basicaly maybe 1-2 times a year), elbow guards not often at all.
When it comes to longer rides i have a pair of fox baggys with the padded insert. awesome, no other word for them. pockets are fantastic, i cant go anywhere withut pockets for my athsma pump, keys, phone bandaids.
I have a camelback, dont know what id do without it. 2L lots pockets.
As for seats, i found it important when i was into xc to have an appropriate fitting one, along the lines of a wtb speed she, or specialised womens. But with dh and djn its not important in the slightest as far as ive found.
One thing ive found important and this may seem odd to a few of you, but after being cornered and harrased by a group of 6-8 males at the train station one day on my bike, ive found that carrying an alarm scares the shit out of them and keeps me safer