To be honest anything is doable - last ride to Norway one of my friends done on Aprilia Tuareg 600 with his wife.
But boy was it slow on open road...
Transalp will do OK in allowed speed limits. If you can stay in them :)
It is by far different bike than GS800 or Tiger 800. Not really same league.
New 700 have a tad more responsive motor but it still heavy and rather underpowered and as fully correctly stated above softly sprung.
It offers no advantages over GS or Tiger but does have disadvantages. Or saying simply - honda should not have tried to revive it IMO.
But 1989 have just couple of curable problems apart from which it is very reliable and undemanding (service-wise) bike that will get you far if needed.
I just recently serviced one of those (engine rebuild) and before I done couple of complete overhauls on them - 1992 and 1989. My conclusion: it does not need much service, but 1989 usually need full rebuild (cure rust and oxidization, check carbs, may need new piston rings etc. etc.) and when you do need to service - it is not easiest bike to work on.