I think your tech friends are talking line-in guitar, because using a
guitar amp miked up doesn't produce such spikes.
Same for my piano, I guess, even if post-effected.
If you are doing
direct line-in guitar you can limit damaging spikes by using plenty of
headroom and a limiter.
I had exactly the same idea.
Limiters are very useful to avoid occasional spikes.
They are used in most "Pro" context (live or studio ).
Try "Voxengo Elephant" VST plugin. put it at the very end
of your signal chain and adiust its settings to "limit" the maximum
peak to a certain threshold.