got an 851 (ok 955) + an RSV Factory, the prilla is great, but there's no way I'd be thinking about swapping what you have for a Haga rep - it's got Ohlins and the bigger tb's and they do go well but the newer model is so much better. You can pick up a Factory for reasonable prices now as well.
Keep the RS250 and chop the 748 for a newer RSV Factory - guaranteed smiles - they cured the drop into the corner problem and you now feel part of the bike