Yes some experience.
I tend to start with just the pressure relief valve open for the first 48 hours or so. If krausen really building up then I put the spunding valve on and set to a few psi.
If you go for lots of pressure straightaway you will suppress a lot of the yeasts character, which is fine for a lager made warm.
As the ferment slows I tend to increase the pressure on the spunding valve up towards the final pressure for the vols of CO2.
I use the Dr Hans calculator to help with this,
https://drhansbrewery.com/beercarbonationcalculator/
Just checked and for Am amber ale recommend 2.3 vols and at 18 C it suggests 22.55 psi
If you were going English Best bitter then you'd want even less vols.
So for these levels not a problem of being near the relief valve pressure.
Regarding that aspect I did put my new fancy Non return ball lock on the spunding valve, not computing that it wasn't going to let any gas out to the spunding valve.
When I returned after about 4 days the fermentasaurus was at 35 psi and very turgid. Could still see the Belgian wheat beer fermenting happily inside. I slowly released the pressure over several hours ( otherwise it's a bit shaken coke bottle scenario) and all was well. Beer tasted fine but not as many esters as I was aiming for probably given the high pressure at the start.
I've also done some lagers and an american ale with Kveik and so this is much warmer and had the pressure much higher around thirty psi no problems.
You may find that you can nudge the temperature of your ferment up a couple of degrees if you have a bit of pressure on the ferment as the flavours you didn't want from a higher temp will be suppressed.
I have both the mostly metal spunding valve and the duotight, I prefer the duotight.
You can use the pressure from the ferment to purge your keg with a jumper lead from gas to gas, or you can fit tubing into the end of duotight spunder and then to ball lock connector on the other end going to the keg to be purged.
Currently fermenting 5 Points bitter clone day 3, and at 5 psi after 16 hours as a bit warmer than I wanted at 20 degrees rising to 22 and have purged keg as above.
There are many other tactics as well. But this has been working for me okay. If you wanted to ferment some Champagne for example they suggest 6 vols, this isn't going to be achievable with a fermenter with a 30 or 35 psi safety valve. In that case ferment in a keg which I understand goes up to 65psi and has a different blow off valve.
