You will most likely get varied responses on this. From where I sit, you are more heavy (you mentioned lifting, so I have to assume a good portion of that is muscle) than the typical 5'2 person. For the record I'm 34yrs ancient, 5'8 @ 162 lbs...sorta a built out ectomorph (Terrell Owens, btw, is the God of all ectomorphs. He shouldn't look like that). We aren't the same heighth, but we are similar weight. I would imagine your leg power to be equal or most likely superior to mine (I'm not lifting anymore).
Anywho, prior to purchasing my 154cm S5 it was came up from more than one bear that they were "too short" for me. I replied that I'm not a speed freak (echoed by you), and that I wanted shorter ones to maneuver at slow speeds while trolling along w/ my burgeoning 12yr old snowboarder (when I'm not carving fighter-jet arcs, of course). Comments on possible ski chatter or instability at speed were also mentioned. Shop I bought from even tried to get me to buy the 161 at least. Needless to say I stuck w/ my guns and bought the carving tool in an SL size.
I've skied them 5x now. Decent local mtn (1600' vert drop, 8200 peak) groomed/hardpack w/ slight afternoon crud the 1st time, not so good slush/heavy wet crud and then surprisingly decent nighttime "walmart powder" (what the liftie called the slush when it hit early night and crystalized, hilarious) and ice patched the 2nd time, then *incredible* fresh shallow powder on hardpack (not a ton, but fresh) and perfect grooms for times 3-5 (11K peak, 3K drop...yup, Mammoth. It truly is Mammoth!)
Verdict so far? No chatter if you let them 'ski' and you don't fight them. Speed instability? A touch playing catch up to my head-starting similarily sized bro-in-law on 180cm Salo Crossmaxes, but I felt that was a function more of the the actual conditions underfoot...on groomed you can control it. And pardon my intermed to advanced novelties, but it actually adds to the drama to have to control the wiggle at speed, lol. Fast enough for me to bomb down blues, fast enough for me to get in enough trouble on blacks. The ski definitely has much, much more envelope in it, so I feel I have only "up" to go in my abilities.
I would say I'm an advanced intermediate or low-level advanced (cuz I don't do off piste or any silly ACL-busting tricks). I'd say we are pretty similar in our abilities and aspirations -- same ballpark. I think most might comment on the 154cm ski to your vertical stature, but I think physcially it's much more than that. At 162lbs or so I can flex this ski pretty well.
All I can tell you is that I'm having A BLAST on 154s. Sure they're not a GS speed bomber -- I knew that going in. I wasn't looking for a Vette though...I was more looking for a Lotus Elise, if you will. I don't need speed I'm not going to use. And with the 154, I can operate w/ a huge smile factor (wait till you let this thing carve it up at medium speed) and NOT risk life or limb to have fun. It does take some work/leg strength to hold the tight inclination turns for an extended period. It does tire you out bouncing from edge to edge. But it sure is darn, darn fun. No complaints whatsoever here. Go for it and keep everyone offkilter