well...
I do not know what is in the MR kits as I have not seen them. The roadwheels are supposed to be pretty nice.
I help sell a lot of T-80 conversion kits thorugh my online shop, click my banner below. Tracks, detail sets, full conversions, and the roadwheels have been remastered for a nicer rim. However, most of the kits I have are made for the SKIF kit.
Also, miniarm has indicated they are going to release a series of conversions/updates for T-80 kits late next year. They have not said which kit will recieve the attention (my guess is the Zvezda/DML kits...not a good idea as the kits are dimensionally incorrect.) They also will probably have a big price tag.
Model Point makes the best replacement barrel, see the reviews section here on armorama for one I did. However, Barrel Depot make a direct metal replacement that is far cheaper but retains all the DML kit problems.
Model Point also make a number of other detail kits good for a T-80...Tuchka mortar barrels loaded and unloaded, antenna bases', etc... Find them at Model Point US
Eduard makes several PE sets, make sure you get the proper one for the kit you are building