I have smoked Dunhill Mixture 965 both from the tin and in bulk. My best analysis is this:
tinned tobacco is sealed absolutely fresh and usually is an optimal example of a particular
blend, but if you order or buy from a good bulk dealer and jar the tobacco (in a sealed canning
jar) pretty much as soon as you get it, it should be the same or nearly the same as tinned.
Any slippage along the way may diminish the quality a little, but if it isn't too bad an assault
on the tobacco, you may not notice, or it may still be satisfying. You can't leave it in the
plastic bag and or stored in heat or humidity. Other than that, blending tobacco is an art
but an inexact science, and you will always get some variation in the year crop of the leaf,
and other variations, so the differences in taste may not be because it is tinned or bulk, but
because of slight (or more than slight) changes in the product or its handling. 1) Try a blend
first from the tin, if you can, and, 2) buy your first round of bulk in a modest quantity to see
if it is enough like the tinned tobacco to suit you. My short answer is, it's probably the same
good blend; buy a nice quantity of something you have liked, and don't worry about it.