I am a heavier jumper than you and I can give you some feedback.
Honestly, the first mistake people tend to do when giving advice to larger skydivers is only considering the WL. Wingloading is one factor that is nowhere near equal for a 170lbs or a 220lbs jumper. I started jumping with a 270 and by the 10th jump I was on 250. Larger canopies with higher wingload will still be less responsive than smaller canopies at the lower wingload. You have to take many factors in consideration, the amount of material, aerodynamic properties of the larger wing, the line length etc.
Long story short, you are not in greater danger just because you jump a 1.1wl 210 and the other guy jumps a 150 0.8wl canopy. Your canopy will still react slower, the roll is longer. The only difference you will probably notice is a slightly faster descend rate and a slightly more responsive toggle.
From what I jumped the canopies in 270, 250, 230 range all reacted very similar. The first noticeable bump came with a 210, but that was also because of the design of the canopy, it was my first non student modern canopy. Still nothing scary. I was loaded just above 1.1 at this point. Then came the 185 which put me under a 1.25 wl. This is the first time I noticed the canopy started to fly in a totally different dimension. But given my flying capabilities, landings etc. I was cleared for it at around 80 jumps. When I made another 60 I was give na chance to test fly a 170 and honestly again the difference was minor, but you start to notice the speed picking up. The lowest I tested was 150 at the end of this season and the leap from a 170 to a 150 is noticeable at worst. The air is louder, you go MUCH faster and you loose altitude very quickly during the turns. Canopy gets ground hungry. And this is definetely my stoping point for atleast 200 jumps. An interesting thing I have to point out is the flare. Flare keeps getting better and better. You can stop a 150 like you would fly a 210, a lot of power available.
Considering the wl:
0.8 to 1.1 pretty much the same, basic flying, if you aren't a total anti talent for canopy piloting you are probably fine
1.1-1.3 Things get faster, sportier but the canopy still manages to forgive some flawed imput
1.3-1.5 The difference gets noticable, every downsize feels like a real step up to the previous size. Things happen fast.
Mind you, this is totally my experience with piloting canopies. I am not saying it is correct, but it might help you, since I already went trough the first few phases. I also must stress that I progressed to a smaller canopy only after I successfully landed the previous model in various wind conditions and situations. If you have trouble standing up landings 280-250 then I suppose downsizing still ain't the right call.
Here is a video comparison I did of a 185 vs a 150 canopy. I'm piloting in both cases. Notice the time needed for both canopies to land. 185 pulls out and levels while 150 keeps flying towards the ground.