Without an xp potion or vip bonus I haven't ever reached 10 points running most heroic content R1 on a first-lifer, although it's close and with new content it might be possible. Pushing difficulty to R2 and/or using potions/VIP would make 10 points easily reachable, but not 20 reaper points. There are quite a few heroic encounters where getting hit with a disintegrate and rolling a 1 is highly likely to result in death, although this can happen below reaper as well. What I found with hardcore pugs is that there is almost always someone that will charge the room, get aggro, assume all the risk and sometimes die. Don't be that person if you want to run heroic reaper. You don't need to be reckless to carry benefit the party.
Some people buy store beholder crystals for all beholder encounters to reduce risk and I've been told the lesser crystals work better so use those - although I don't have the details as I don't buy those. If you are in a group things go down so fast you should get alot of use out of one crystal.