For anyone to say that a spring weight affecting shock seals makes no sense.
In motorcycling there is a long standing debate regarding softer dampening with heavier spring vs. firm dampening with a softer spring. Neither affects shock seals.
Only miss-alignment or abrasive material would cause a seal to fail.
One could compound the firm ride with firm dampening and heavier spring rate. Or, the alternative with soft dampening and softer spring rate.
The key to good suspension is to determine what you desire and select dampening and spring rates to match. The off-road racing suspension I had offered slow speed soft dampening with progressively firmer dampening with speed, and matched springs.
To answer the original question, my recommendation would be - yes, get a stiffer strut. I have the KYB GR2 gas struts and very satisfied with them (albeit they are on OEM spings). I did a lot of research on struts as I was lifting my fozzie 1 inch with ADF spacers (highly recommend!). Read that monroe struts are softer and problem couldn't withstand stiffer rates, whereas the KYB are valve higher and can withstand a high spring rate.