I found transplanting roses in March works best...For here anyhow...lol

If you get very cold winters than spring when the rose is dormant is best If your winters are reasonably mild, then fall when the rose is dormant or has dropped all it's leaves. Don't cut the bushes back below 2 feet as some roses resent hard pruning. Transplanting a rose isn't the difficult part, keeping it alive is.

And save as much of the root system as possible, but don't kill yourself doing so. You'll lose some of the roots -. just do the best you can.

I think one important thing is to quickly replant after getting each rose out, leaving the now exposed roots exposed for as short a time as possible.

I had no idea when I started my rose obsession the horrible war I'd have with ground squirrels and gophers. After about 70 roses were planted, up to 4 years old, I started finding roses over on their sides, with their entire rootstock eaten. I refused to let this happen any longer. I dug up almost every one of them (except a few that i said - if the gophers take them, then I don't have to shovel prune them), lined holes with hardware tape and chicken wire, and replanted. I did not lose a single rose from this process. I did it in October, and did cut them down to about 2-3 feet (so I could maneuver them).

New planting bed. Gopher mound between Violets Pride and Great Century. These mounds are everywhere between my caged roses, but they don't kill the roses!

When is traditionally the best time where you are to plant bare roots? That should be one of your guides for transplanting your roses. Definitely attempt to retain as much of the root zone as possible, but as has been suggested, don't kill yourself doing it. This rose has a good breeding line and has to be "vigorous" or it wouldn't have the cold hardiness it has. The worst case scenario will be having to bare root them, which may not be all that bad, particularly if you can transplant them just before a period of rain. Rain will keep them bathed in moisture which prevents them from drying out, while it also settles the soil around the roots and triggers the roots to reach out and establish themselves more quickly. Yes, definitely prune back the tops in balance with the size of the roots. It is always better to have more roots than top growth rather than vice versa. The plant will shed what it can't support or doesn't need. It's better to have more below ground than above. The prime directive is you don't want them to dry out due to too little root compared to top growth. If you can expect warm-ish, sunny, perhaps windy and drier conditions when you transplant them, hill them with soil or mulch to keep them damper until new grow begins to show. If it will be cooler and wetter, no hilling should be required. Just let the rains keep them moist and settle them in. If you transplant in fall, I would winter protect them, presuming you practice winter protection, using whatever method you prefer. If you don't normally winter protect, I wouldn't think these would require it. Just treat them as you would any newly planted bare root and you should be fine. Good luck!