Talking about a relationship to OPT ALT while discussing turbulence is meaningless unless you mention the a/c type.
What a/c impacts the spread between OPT vs. MAX ALT. 737NG w/winglets is approx. a 1700' spread. 777 is approx. 3800' spread between OPT/MAX altitude. So OPT ALT in a 737NG w/winglets is 1700' below MAX. To get 1700' below MAX ALT in a 777 would put you 2100' above OPT ALT.
For Boeing's the larger the a/c the better it's buffet margin performance is while at OPT ALT. Most a/c can maintain OPT ALT at 1.3G turbulence but some have to descend. At 1.5G turbulence at OPT ALT most have to descend but some can climb.
I'm not sure if this is related to the buffet margin differences mentioned above but at OPT ALT the 'window' between the max and min speed tapes on the 777 is about 50% greater than on a 737.
X number of feet below OPT ALT? IMO not a factor.
Bank angle reduction? IMO that's a good technique for all high altitude ops.