As far as caliber, I really dont notice a difference in recoil vetween a 470 and a 500 assuming proper fit and weight. Also, if you are looking at vintage DR's, 470's tend to cost a bit more then the same gun in 500 from what I have seen. Personally I prefer a 500. I would not get a 577 as a first double as it is heavier and quite specialized.

New/Vintage...

It really depends. They both have their place in the world and their own pros/cons.

If you buy a vintage rifle make sure you buy from a reputable dealer and also have it sent to a third party with lots of experience with DR's for a check up during the inspection period. I think accuracy between the two is kind of a wash.

A couple cons that I see with buying a vintage rifle are...

No warranty. If something breaks, you will likely have to fix it out of your own pocket which can be $$$$.

Price tends to be higher then the various entry level Heym, Searcy, Chapuis, Merkel's.

It isn't built for you so you can't specify which options you want/don't want and you may have to alter the stock to fit you.

If you don't reload may be a pain to get ammo that shoots to regulation.

You can really get taken if you dont do your homework and due diligence.

Pros for a vintage rifle;

If you buy right and take good care of it they will almost always appreciate in value.

Seem to be more svelte and sexy then the modern offerings and I would say balance better as a whole (Pre war brit).

Fit and finish tends to be better on vintage rifles from what I have seen.

Pros for a new rifle...

Can specify options on some makes (Ejectors/extractors, stock dimensions, reasonable changes in weight, bbl length, regulation load, Sights, Wood quality, etc...)

Warranty.

Tend to be less expensive.

Modern steel.

Can be regulated with factory ammo or a known load that is easy for yourself or a company like Superior Ammo to duplicate.

Cons..

Depreciates (not usually that much though as the price for the same rifle will go up over the years that you own it.)

Balance, fit and feel. This varies from maker to maker. Some are a bit clubby, some handle/balance very well (in my opinion). Just need to handle them and see what fits you the best and is the most comfortable.

Wait to get it can be looooong.

If you are looking at new rifles I would take a serious look at Heym and Searcy & Co. Both are very good rifles, are in your price bracket, are relatively bomb proof, quite accurate and I think handle very well.

If Vintage I would take the advice given above and stick with Pre War British.

Good Luck and keep us updated.