Possible but not optimal, depending upon what you're trying to do. They're great for filling in holes in your gear, as pointed out, but you do sacrifice some longevity from it.
I found a necro post of mine:
http://wow.allakhazam.com/db/class.html?wclass=8;mid=1196701941185571746#m119671488429599953 wrote:
Arena epics work as great fillers because they have such a great iLevel compared to how easy it is to get them. However, not all of the stats are what you're looking for in PvE--which is why I'm iffy about using the whole set.
Gladiator's Wartide (123 iLevel)
3517 armor
301 healing
19 mana/5
219 Stamina
106 Intellect
100 Spell Crit
125 Resiliance
Cyclone Raiment (120 iLevel):
3435 armor
374 healing
39 mana/5
169 Stamina
171 Intellect
Gems balance out. So you're sacrificing +73 healing, +20 m/5, and +65 INT in exchange for +50 STA, +100 spell crit, +125 resiliance, and a lil armor. Raiders have a health minimum so STA isn't all that bad, but you can have TOO much if you're sacrificing other stats for it. Resiliance and armor are next to useless for a raiding healer, and spell crit is usually just overheals.
The problem I see all the time with PvP geared healers is longevity. A 2 minute arena match is a very far cry from a 10-15 minute boss encounter. PvE resto shamans rate +m/5, +healing (for downranking), and INT (to a lesser extent) very high to increase longevity, and the PvP gear just doesn't have much.
PvP heals need to be quick and powerful, PvE heals need to be slow and steady; this is reflected in the gear. Thus, switching gear roles is possible but not optimal.