as someone already said i'd go for the a5, so much better and not much more expensive than a 98 new,
but as that wasnt the question...
98 as far as i'm concerned has unbeatable durability, i'm a marshal at a site and we use 98's as the main marker, as do alot of sites..
i've seen them dragged thru pretty thick mud....dropped in a river.. then pulled out recocked and still worked..
there is a reason they are used as a site marker.. cos they a freaking hard to break...and if they do..there easy to fix.. a 98 was my first makrer and i loved it.. so yeah i'd go for a 98..
but dont think i havnt used a bt4, mate of mine broke his ...dont know how... he broke it...lol
so yeah i'd go for a 98 much more reliable marker...also ...has more upgrades than a bt4..duno who told you didnt