7x19 or 6x19 IWRC too flexible?

[redbopeep]

I am replacing 3/8" 1x19 SS standing rigging. Since I plan on building and maintaining the rig myself and I have little hope of competently splicing 1x19 wire rope (I can handle 7x19...just learned--thanks to the Riggers Apprentice and 35' of 7x19 and a bunch of thimbles...),

I am looking at using 7/16" 6x19 IWRC in 316 SS (larger size to meet the strength needed) or using 3/8" 7x19 galvanized which meets the strength required (with all the required serving...)

3/8" 7x7 while stiffer doesn't meet the strength requirements (and can't find it anyway...) OK, now, big question--are either of my wire rope options (which meet my strength and "splicability" requirements) going to be ok in standing rigging application? The concern is whether it would have too much stretch or the flexibility will be a problem--if so, how?

Thanks!