Had practice today and found an 8 ohm monitor in the pile of questionable gear the drummer has in his basement so I stuck it in the second speaker out on the head. Didn't hear any noticeable difference in terms of power/quality coming out of the 410HE with my aforementioned settings (Gain to 10 and Master at 2) and the wedge didn't sound too bad (no farting/breaking up) even though its only rated for 80 watts RMS. I guess this will do until I find a suitable replacement cab.
No promising listings on ebay or craigslist for my needs at the moment. I guess my price range puts me in an awkward gap as 4 ohm 410s seem to fall into one of two camps: under $500 and mostly crap and nice cabs that are $800 and over. Nothing really in between as far as I have found...
Yeah, I hear you on the price gap. That 80W monitor might not last long. If you cant afford a quality replacement for the 410HE, a couple of bills for a used 300w monitor will have to do. Whatever you do, avoid running 8ohms off of that head. Transformers are expensive.