EIDW, if you are used to flying the Warrior you will find the conversion to the Arrow extremely straightforward, its almost exactly the same except for that extra blue lever!! Its flys just like the Warrior, but a little bit faster.
The ones I have flown weren't like "mini-airliners" though!!! They are nicer than a Warrior but to be honest they are not that exciting once you get over the "ooh, I can raise and lower the gear" part.
In the US they have to give you a complex check out. If you have a UK licence I assume its the same now with the new JAA ruling on complex aircraft types. Also, there is sometimes an insurance clause requiring a certain number of hours for the check out.
Personally, bearing in mind the fact that the difference between the cost of flying an Arrow dual and the cost of flying a twin dual, in the USA, is minimal, you could do what I did and just get a twin check out.
If you wanted to, and like flying in the USA, you can do a multi rating in as little as 6 hours (I did mine in 6 hours, having only flown the Warrior previously, and having only done my PPL a couple of months earlier). If you wanted to also do the FAA medical, the PPL written test and learn about your aircraft, you could do an FAA multi engine test and get yourself an FAA licence.
Its actually very easy, gives you something to work towards, and only takes about 2 days for the flying. The other stuff will maybe take one or two days to cover.
Either way you will get some more hours in the book, learn loads and feel you have really achieved something, as well as fitting in all your single engine stuff too.
This is how I did it and I
So my advice is, do all your hour building in a Warrior and do a twin rating. Or just do the Warrior time and fly an Arrow for fun.