This isn't a discussion about how level 70 SAM plays, but rather how the feel of the class changes as you level up and unlock the kenki gauge.
Yes, I know this unlocks at level 52, and SAM starts at 50, so for a bulk of the road to 70 you'd theoretically have the kenki gauge. Practically speaking, though, I've gotten very little opportunity to use it so far and I'm close to 60. Why?
A quick look at the main sources of exp:
Leveling Roulette: For DPS, you're very unlikely to get anything above level 50.
MSQ Roulette: Always level 50 Sync, and everything dies quickly.
Alliance Raid Roulette: Unless you're 60+, you will be synced to level 50, and even if you are 60+, people don't jokingly call this the "Labyrinth of the Ancients roulette" for no good reason.
PvP: Doesn't use your PvE skills anyway, so can't practice PvE skills there.
PotD: Most things die so fast it's hard to practice the rotation for any class.
So, outside of the striking dummy, there's not really a good way for anyone (not just SAM) to gain practical experience with their class until level 70.
With every class I've played in SB so far, this hasn't been much of a problem. Having a given gauge or not usually just means having or not having access to certain actions that just build on top of existing actions. Nothing about previously learned actions changes fundamentally.
With SAM, however I found myself rather confused as to why the kenki gauge was filling far slower than I had anticipated after a quick reading of the trait for it and such. At some point I was doing some FATEs for a quest in HW areas and paid closer than normal attention to the gauges as FATE mobs are usually quite easy and finally noticed what was going on: Not only did I need to land the combos I had from level 50 already, but that they suddenly had positional requirements that didn't previously exist which only serve to build the gauge.
Of course, soloing FATEs meant that I wasn't going to easily land many positionals, so I figured I would keep it in mind for the next time I took my SAM into roulettes. Unfortunately, this idea wasn't so effective given the fact that I'm pretty much always level synced to 50 or below while running roulettes. To compound that problem, if you don't have the gauge due to level sync, the tooltips won't show the positional requirements! This makes refreshing my memory as to what they are in a dungeon as well as getting feedback to if I'm doing the positionals right in leveling content very difficult.
Basically, this shift that happens for SAM at 52 feels a lot like BRD in 3.x with wanderer's minuet. Granted, the shift is arguably not nearly as bad as BRD had it, but BRD at least got (after balancing) a direct, visible damage boost from that shift. For SAM, it's a very subtle boost to your gauge that otherwise doesn't affect your main combos. I have to wonder how many players out there even realize SAM has positional requirements. In fact, prior to actually trying it out myself, I was under the impression that SAM was unique in being a melee DPS class without positional requirements (presumably because of Iaijutsu and the kenki based skills already adding complexity with reactive skills that required actively using third eye with correct timing).
To top it off, Yukikaze even adds to the kenki gauge without a positional requirement. Due to this, I had noticed the gauge filling and being able to occasionally use kenki-based skills, so I was under the impression that I was doing something right (at least in the heat of battle during the one time I was in Sohm Al with SAM recently). It felt in line with comments I had heard before about the guage filling very slowly so I didn't even think to question it until I was soloing FATEs much later.
Don't get me wrong. I'm not so much complaining about the fact that SAM has positional requirements at all, but rather that it goes from not having them to having them based on if you're synced below level 52 or not. If the SAM combos had the positional requirements all along, it wouldn't come as big of a surprise, and I'd be able to more intuitively practice them at various level syncs instead of strictly at high levels.
Personally, I feel like SAM could benefit from having the positional requirements dropped. Not only would it keep the class intuitive at most levels, but I fell like it is already "complex enough" without them. Plus, it'd fill a niche for players who might like melee classes, but are bugged by positionals. Alternatively, some sort of bonus could be applied to those skills that have positional requirements for the kenki gauge to give low-level SAM a feel much like the other melee classes at low levels. Perhaps swap it to give full potency for correct positionals but always build kenki.