I'd be curious your experience with the mx450 from that, as all of ours are tipping over still after RMAing us from mx600's. Using them in sdwan with upward of 1100 mx's in autotunnel to the hub(s), they can no longer keep up, particularly since 16.x last year, and support actually suggested they'd upgrade us first (then sales fought it, no commish in free!). I adopted these for a customer after their last meraki guy ran away, and found out quick that 5000 max vpn count in the data sheet is a joke when things started breaking. First the number given was "real world some ~1500" tunnels we heard from cisco, and the reality is they can't do much over 1100 now on the mx600/450 with them pooping out at some 85% usage. Now faced with random outages they're having to shard all our branch networks out across 5 hub locations and soon a half mil $$$ later, the customer is not terribly happy.
Sad part is Cisco doesn't themselves have a good reference guide for sharding networks for very large branch quantities across hubs since the wilette.works site died... Good thing I remember it to recreate.