I only have a few runs on the Laser AX 183 cm ski in really soft manky snow. It didn't feel too long to me, just right actually. I typically ski a 184 to 188 cm ski, so the 183 is in my wheel house. Its not a ski that feels really long, although this ski did feel that way to James and MDF.
OP, if you are skiing a 177 cm ski, then the 175 AX won't feel any shorter. The 183 will feel longer for sure. If I get on a 178 cm ski, it feels short to me. I am 6'4", 240lbs. I think the Laser AX is a ski that doesn't feel short for its size, if anything slightly long. When I demo'd the ski I bought, I was probably -1 cm (behind the line) and it felt OK, but I would say I wanted to be a little more forward on the ski. In the soft snow I was in, I was impressed with how good the ski felt. I have a Kastle MX 78 in 184cm that feels awful in snow like that with me on it. Very grabby and super small sweet spot. The AX was so easy to ski, it didn't feel like a 78mm wide ski, it felt much more stable than it should.
My advice is stick with the 175 AX unless you are looking for more of a GS ski, which most people are not in this type of ski. The ski is soft feeling initially, so the longer length is not hard to ski, but I think it takes some strength to wip it around. Bigger guys seem to like the 183 length with the bindings moved forward 2-3 cm, per Jame's advice. Some skiers claim if you drive your skis and keep your weight forward, mounting on the line is best. I won't know what works best for me until next season. Sorry I couldn't be more help.
If you own other skis, what size? The AX skis pretty true to size, maybe slightly long, in my opinion.