A bit of history, here...
Gun Digest (I believe it was in the Handloader Digest) a year of so before Smith came out with the 36-6, ran a nice article by a gentleman who had built a similar revolver for field use. I was counting up my nickels to see if it was practical to have one gunsmithed for my self. Money was rather tight, back in the day, but the concept really caught my fancy.
I just happened to be a the Indy 500 gunshow, a low and behold, they had a couple of the 36-6's (limited edition). I didn't have a lot of cast with me, and, not realizing that this was a VERY limited edition, I passed. Well, I stewed and stewed and could hardly wait until the next Indy 500 show. I got there and discovered that there were NO MORE. Oh, woe is me (he who hesitates is lost, etc.).
However, they had the NEW 60-4. I was disappointed that it didn't have a 4" barrel. I'm a shooter and didn't have much faith in the shorter barrel. 4" would have been perfect for my tastes. Oh well, didn't want to pass it up, again, so I took one home.
I got to the range and was nearly blown away by how much better the double underlug barrel held. That extra bit of weight out front more than made up for the short barrel (compared to my 631, as a for instance).
I won't repeat the scores that I was getting at 25 yards for fear of being called a liar, but it was eye opening for both me and the shooters around me.
It made a perfect companion piece to my bird gun (Beretta Silver Snipe over/under) for those sitting rabbits, etc. I took a number of cottontails, snowshoe rabbits, and wounded and sitting grouse with that piece and it will be one that I will own until I can no longer shoot.
Just goes to show that sometimes, just sometimes, you CAN teach an old dog a new trick...
Back on topic. Yes, it is safe to shoot occasional Plus P loads in the 60-4. A most effective load is Ed Harris' "full charge wadcutter" - it is a standard pressure load that is VERY effrective and will not beat up the gun.
http://www.grantcunningham.com/blog_files/75f11fe4e235da7c69cabf94daa7dbd9-932.html
Dale53