Have you tried another ammo with known performance to see what velocity it has? Perhaps Federals gold medal 190gr bthp. Otherwise you just have a slow accurate barrel and I would take that any day over a fast shotgun.
The taper lock is clearly stated in all of their literature so it would be up to the buyer to understand this before the purchase. I have their QD mounts on several hosts and none of them are cut specifically for the taper lock. All of mine snug up fine to traditionally threaded barrels ranging...
Those off-road electric carts have come a long way. Very powerful and quiet. I really like them. Just don't get stuck 😂 very hard to get out with the weight of the batteries.
The sigs are also pretty good for the money. The zulu5, 7, and 9 all have a 10x so depending on your budget you pick the cost. I have the Zulu 9 11x45 and love them.
Since this would be your first can, go with a 30 cal. That way it can handle all of the ones you have mentioned and is a bit more future proof. Then go from there to get ones for specific guns that will not change hosts. The thunderbeasts are excellent cans, but maybe check the sigs as well. the...
That seems slow to me. Speed is not the end all be all in my opinion. Accuracy and repeatability are what I look for in hunting ammunition. If you have good repeatable dope for that ammo run it and don't worry about what the chrono says.