Reel-to-reel is better than casette, no doubt. But you need a mixer too, not only the reel-to-reel. If you can get an 8 track r2r with mixer for $600, that would be better than the 8-track casette porta, and you can also "upgrade" the mixer separately. However, since 8-track casette portas seem to be around $600, I don't think 8-track r2r's with mixers will be that cheap, unless you get lucky.
Reel-2-Reel is not always superior to a digital 8-track, though. Digital 8-tracks that can record on more than two tracks simoultaneously is usually expensive, so if you need that, a r2r would be a cheaper alternative. On the other hand, of you have no outboard effects some digital portas have their own, which is nice.
Summary: For someboy starting off with no equipment at all, a digital 8-track with built in effects would probably give you the most bang for the buck. However, if you (like me) already have a mixer and a lot of outboard effects, and have been using a 4-track just as a multitrack tape deck, then a second hand 8-track r2r would probably be a better choice than an eight track porta. OR you could (for slightly less money) buy an eight-track casette deck (like a porta, but no mixer). They should be lots cheaper than a porta and cheaper than a r2r.
In your case, with the Mackie 1202, you will probably soon find yourself longing for another mixer if you go with an 8-track casette deck or r2r.
Head spinning yet? It's not an easy choice...