A lot has been said about this ski, but I wanted to add my 2 cents, having finally got these after thinking about them for a year or so.
About me: I'm 39, 5'9, 170lbs or so and ski primarily at Tahoe, with a trip to Utah every year, if all goes well. I put myself in the upper echelon of the SF Bay weekend skier crowd. I have decent technique and ski everything with confidence at reasonably high speeds. I do not ski like a former racer or 25 year old local stud.
I haven't skied a ton of skis over the years, so that's a relevant point here. I''ve had first generation Bandit XX's (not so great), Pocket Rockets, K2 Crossfires, and Gotamas. Still have the PR's and Gotamas. I've demoed Salomon Fury's, Mantras and Watea 84's, and Head 82's. This is really the first multi-metal heavy duty ski I've skied on, so I'm sure others are similar in some respects. I was looking for a hard snow ski, specifically for spring Tahoe days, where it starts on very firm groomers, then the off-piste opens up as the sun allows. The Crossfires, at 68mm, were simply too narrow and flimsy for the variable conditions that come up, but I still wanted something carvy, hence the 78's. I tried the 177, on hard snow only, and elected to go with the 171. I'd like to spend some more time on the 177 if I ever get the chance, to see how versatile it is in tight bumps etc.
I was blown away by this ski. In short, it is tremendously stable, solid, and quiet, but does everything I ask of it without protest. It feels like it is glued to the snow and just removes any chatter or surface irregularities like they aren't there. I have found it to offer super high levels of performance in all conditions, yet it is not in the least difficult to ski. They like to go fast in all conditions, but are easy to control. There have been many wow moments as I got to know the ski.
First, on icy morning groomers, the snow types and transitions just don't seem to matter. Just arc across them without a problem or shock as the snow transitions. If you want to line up the run and do it in 2-3 turns, no problem. Super stable at speed. What's remarkable is how they quiet the snow and isolate you from the ice, etc. They seem to do all turn shapes well, from quick side to side rhythms, to opening them up. Lots of fun. This stability comes with a trade off. They are not super snappy or energetic, but more calm and sure.
Loose snow and crud were a big surprise. I just arced through it with no fuss. The tip on these things is actually bigger than on my PR's and not much smaller than the Gots. I purposely went through some refrozen crud and hardly felt it. Nice! I haven't had that on the lighter skis I've been skiing.
The biggest wow, and something I can't get out of my head when I go to sleep, came on a super steep bump run on decent, but variable snow. Firm on the back of the bumps, some cruddy fluff around the troughs. This is the kind of run I love Squaw for, where if feels like you're descending 10-20 feet of vertical for each long mogul. This ski gave me options I've never had before. I could flow with the shape of the bumps, OR I could carve wicked fast turns as I came over the top of the bump on the frozen backside of the bumps with complete control. The tight radius and stable, grippy nature of the ski made it easy to just turn on a dime in almost no lateral space. It was like dicing up the run with a scalpel. Super quick, no skidding turns any time I wanted, but I had no trouble floating or sliding as necessary. Again, really easy to ski. The ski makes everything feel smooth. That said, when the terrain leveled off a bit and it was zipper line time, I couldn't just mash the ski around the bumps like with my Pocket Rockets. They are a firm, reactive ski. But they don't throw you around or take you for a ride either.
One reviewer commented that he liked the Watea 84 for soft snow and I can see that. After all it's a bigger ski. I demoed the Watea and was impressed with how it held on firm groomers for a light ski, but the feel is totally different. They are more like a higher performing Pocket Rocket, soft and playful, but the Head's just smooth and level everything out for you, inviting easy speed. On soft fluff, who cares, but for the variable conditions I got them for, they are ideal.
I would recommend that anyone looking for a midfat put these in their demo list. The performance and versatility are awesome. They aren't a snappy, poppy ski, so if that's the feel you're after, I don't think this would be the right ski.
One thing that I found, and it's been well commented on this forum, is that the factory tune sucks. They need to be reground and the base edges reset to 1 and a side bevel of 2 or 3. I went with 2 because all my other skis are 2 and I wanted to compare apples to apples. Given the performance was as good as I could have asked for, I'll stick with it for now. A lot of people have recommended a 3 side on the Monster series, so you may consider it. It's a shame that they come out of the factory jacked up, but just get them retuned right away and that's that.
Happy skiing!
] IM78 is not for everybody, but it’s a well balanced ski that hits 90% of my everyday skiing [summit and eagle counties] including crossing over and managing the occasional ice fused birds of prey downhill or an off piste frankensnow encounter. 
] IM78 is not for everybody, but it’s a well balanced ski that hits 90% of my everyday skiing [summit and eagle counties] including crossing over and managing the occasional ice fused birds of prey downhill or an off piste frankensnow encounter. 
wow...I only shared those figures with Betsy after a few dates. I will however tell you that I'm 6’ 3.5” @ 198lbs 
wow...I only shared those figures with Betsy after a few dates. I will however tell you that I'm 6’ 3.5” @ 198lbs 
