We (2/5)had one with us at Fortsill, and with us at CampCasey(1/15). I'm not a mechanic so I never had the pleasure to operate either but they were soo interesting to watch.
In korea once, I watched it distroying a road because of it's size. They made the driver park on this little road and you could see the cracks forming as it moved. It sat there about 6 hours during through the night while we did firemissions, and in the morning there was a very nice reverse plateau in the road that wasn't there before.
The M88 was said to be able to push 1 tank and pull 2 at one time --- never seen that and I doubt it could do it, But have seen the M88 pull 2 disabled tanks over rough terain at the same time.
As to it's power I got to witness that a couple times. We had a support hemit park next to us (fortsill) for the night. in the morning when the drivers woke up , the Hemit had sank till the ground was keeping the passenger door closed and about 2 inches from the bottom of the drivers door. There was some nasty mudd and rain during those field menuvers. We brought in a M992 to pull them out. Now the M992 is not a wrecker, but it's got loads of traction with nice tracks and it's use to carrying a heavy load of Artillery ammo and it's got a decent strong drivetrain. on top of that, we had three within shouting distance. We hooked up the 992 and watched it dig a 2 foot trench pretty quickly. Then we brought in a second 992, and hooked them up in series, and got 2 trenches for our effort. about the time we finally got both 992s out, the M88 was finally arriving (I think one of the Mechanics told me once that it had a top speed some where near 20mph). Once we got it hooked up , it popped the Hemit loose with no effort at all. I was always impressed with that machine.