I've ridden a ton of gravel roads on my Suzuki GSX-S1000 and never had any issues. Never even had a dent on the oil filter and it's right behind the front wheel.
Oldgreybeast, with all due respect, I'm more than familiar with your type of reaction. In the past I've warned unnumerable times for the risk of running inline fuel filters on a CB500/550 and I have shared my personal experience with them. More than once a person thought it necessary to reply: "O, but I have ran them for years without a problem." Such a reaction is trivial, anecdotal at best and has little value against a serious warning.
BTW, in this thread you will find evidence that a spin on filter can indeed lead to trouble. True, that post is also anecdotal, so a reader has to weigh its value against your post.
It is my wish that in this forum there were less reactions like yours, where others know better from experience. The latter posts have a warning where yours is trivial.
I have a dozen motorcycles in my garage that all have spin on filters save 1. And all that have spin on filters have way more miles over all types of surfaces than the “housed unit” and none have ever had an issue of “puncture” as eluded to. The shape of a cylindrical metal-walled filter is more likely to deflect debris than allow penetration. There are far more occurrences of members struggling with a corroded, stripped housing bolt than anyone ever reporting a filter puncture.
“Sharp gravel” is a ludicrous statement. Gravel used on road surfaces gets pulverized constantly by the traffic on it and is far less likely to damage a filter that is nearby than a windscreen that is farther away due to velocity and momentum.
Your “warning” is anecdotal at best and based upon a lifetime of rejecting modern advancements and principles of designs and engineering research. As for the OPs preference, if he prefers the stock aesthetic, run the housing and take precautions to avoid corrosion issues. If he prefers a spin on and its potential benefits, run that.
Find a filter you have confidence in that meets or exceeds the 40+ year old factory spec, and install it and ride the damn bike. But restricting choices to decades old approaches in the face of engineering evolution is bewildering. If you want to remain a purist to stock, that’s good with me. I’ll take better than stock because traffic, roads, and speeds today are higher than yester-century’s and I want to enjoy my time inside the helmet and not worry about my safety, reliability or performance.