You'll have to deal with the trigger wheel issue anyway, it's not a problem that you need to worry about.
The V4 is a very good deal/ecu, I went Emerald as I live 1/4 mile away, and known dave for years, plus I like the designed in house, made/built in house, mapped in house, dave is the most honest helpful guy you could meet, but some others are as well, just weed out the bad ones first!
The K3 has also been modified to run 5 cyl engines and twins, as well as Charlies 27,000cc rolls royce merline engined 24 injector 2 distributor set up, but this ecu was STANDARD, not modified in anyway.
I think location would be something to look at, there are many good mappers, as well as many crap ones, but don't go trawling the whole uk if you don't need to.
tabetha