Scott,
The 450's are still the top dog as far as sound quality goes, but I just traded mine for the new EV SXa100's. I got tired of huffing and puffing - the EV's are much easier to carry, and what little I miss....I don't miss, really. If you have a chance to maybe exchange them - at least try them out -they are very impressive.
The advantages are threefold -
1) lighter & smaller
2) on board EQ (hi & lo EQ)
3) two channels each - mic and mic/line
the line input has a dual XLR/quarter inch jack (neutrix, I think)
If you decide to keep the 450's - there is NO problem with just using a cable with 1/4"male at one end and XLR male at the other. These are readily available everywhere, and most are balanced (no problem there)
The 2k speakers will handle a small cocktail party or average nursing home crowd of about 40 - 50 people. After that, you'll be pushing your voice too much because of the top facing speakers. In most cases - it's fine, but as the room gets noisy - the vocals get lost. Talking is also not as intelligible at moderate speech levels. I predict that you'll be happy 95% of the time with the senior crowds. They don't WANT too much volume.
One Mackie will handle 200-300 people EASILY if it is on a stick and in the center of the room. The horn has the best dispersion I've heard yet. Two of them....well - that's just heaven. The only time you will need more is if you are playing a lot of bass-intensive stuff. That can use up all the headroom fast and you may get a kind of "splatty sound" The 450's also tend to overheat when pushed to limits. Keep LOTS of ventilation room behind the speaker, and NEVER use them on their sides on carpet, in corners or when playing real loud - they will definitely overheat. (take about 5-8 min to come back on) I guess a small fan blowing on the heat sink may eliminate this, but they are sensitive to heat.
I really prefer the 450's to my new EV's but I opted for the comfort factor. That's why I'm using the PSR2k - it's not MY FAVORITE CHOICE but it IS easy to travel with.
I'm not trying to rain on your parade, but you owe it to your self (and your BACK) to listen to the EV's - they're so close sonically, but much better to travel with.
Good luck, whichever way you go with it.
So far, the 2k and the EV's are a good combo for me. Small, powerful, attractive .......
A lot like a girl I once dated!