From what I can see, it's a grind tank to get to Tier 10. The advantage of it is that it can never be bottom tier. The disadvantage is that it doesn't get to club Tier 6 seals. My question to you is, do you really want to start a totally new crew on a Tier 9 tank? I understand your thought of keeping the ISU, it is fun to play...but I wouldn't want to run either of them with a crew that didn't have at least the Camo perk completed. I'm going to run my crew up and grind out the 704, mainly because I refuse to spend the cash required to convert the xp to bypass it. With the lower Russian TD's on sale this week, I'm probably going to buy a SU-85 and grind a second crew back to 100%+100% camo to either buy back the ISU and run it later, or to try on the second Russian TD line. In my experience, the higher you go, the more important it is to have a trained crew with multiple skills/perks if you want to have sucess. For reference, my 4 out of my 5 ISU crew will be well into their 3rd perks before they get onto the 704, and the 5th will be right there, maybe just started, depending on how much I run my 122-44.
'09 Kawi Versys
"A life is like a garden. Perfect moments can be had, but not preserved, except in memory. LLAP" - Leonard Nimoy