personal preference, but the only reason I would go for the big phil backyard model over the blue smoke would be the insulated firebox. plus it's much more customizable in terms of length and etc. I like the idea of an insulated box, but I'm not sure if it's worth it to me yet.
The insulated firebox is an interesting topic and not too much information out there on it, and conflicting at that. I've heard a few say that an insulated firebox on pits smaller than 250 can create an "oven" effect, or essentially you only can burn smaller splits/less wood. On my 1975 I can burn some big fires compared to the snippets I've seen of 94 gallon pits with fully insulated fireboxes using much smaller fires (not confirmed but just the glimpses I've seen).
-Moberg used to build a backyard pit with fully insulated fireboxes - hard to dispute his building techniques and his pit's performance.
-I know Primitive recommends a semi-insulated firebox, not fully insulated, on their 250s in warmer states.
-I noticed in Franklin's PBS pit building video he stressed semi-insulated for even his bigger pits, not fully insulated.
It's hard to say if there's an advantage to building a bigger fire, perhaps more flavor? When I run my pit with a bigger fire/slower draft the food tastes much better, but that could be from the slower airflow.
On the other hand, a fully insulated may be beneficial for those in areas where wood is expensive or hard to come by, and the safety factor of not having a scorching hot firebox. I would love to hear other's thought on this, since there's a lot of assumptions I'm making.