Between a 6.5x55 improved and a 6.5-06, I'm not sure there's much difference. Again, for me, I'd lean towards a 6.5-06 because I've got a mess of 30-06 brass...
So is the 6.5X55 improved as big as an 06'? I'm new to this caliber and just think it is another .264 caliber. If that is the case then I will go the route of the 06'.
"Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it.  But small is the gate and narrow the road that leads to life, and only a few find it.
If you find your self in a fair fight, your tactics suck!- Marine 1st Sergeant Jim Ryfinger
Friends don't let friends develop canonitis!-chucknbach
arguing over the internet is like the special Olympics....even if you win, you are still...special!
As far as the .260 Rem. brass quality issue. I just received a batch of Nosler Custom .260's. I have to say they seem to be on par with Lapua and perhaps slightly better. They are truly ready to be loaded....they've been trimmed to length, chamfered and the flash holes seem to be drilled like the Lapua's....also pretty nice they are weight sorted and packaged.
I've got a new project rifle. It's based on a Remington 700 stainless short action. Bartlein did the smith work and put on a 31" stainless medium palma barrel. She's chambered in .260 Rem Improved. I'm looking at using the 142 gr. SMK's for 1K BR shooting.
The 6.5mm x 55 swede sure looks interesting....as does the 6.5-06...but I didn't have a spare long action around to try one.
I searched that 6.5x47 and it appears to be a sweet deal, especially if building a gun on an existing action with limited mag length. I was fantasizing about changing my tikka, and with the slightly shorter COAL of the 6.5x47, there would be no worries about seating depth....
I just got a 6.5X47 rifle a few months ago. It's my first and only custom rig. I love it. Was shooting out to 500 yards yesterday and it was putting 4 shot groups inside 2.5". I s'pose this has more to do with the quality of rifle than with anything magical about the 6.5X47 cartridge. But there's not much recoil and it launches 123 grain scenars at a decent velocity (I'm shooting 'em at 2,800fps, but they can be pushed faster).
It'll work great on deer and other medium game; and, I'm sure it would be a good choice for groundhogs where you won't be doing a lot of high volume shooting.