Levinson 331 upgrade to 331.5

I bought the 331 used and the list price for the .5 upgrade is $1,900. It seems rather pricey when I considered what I paid for the 331. Love the amp as it is, but would consider the upgrade if it could really take it to a level that justifies the cost. If anyone has been in my shoes and done the upgrade I am very interested in their thoughts and opinions. Thanks much.
Invest the money and then buy the 334 instead. I have the 333 and have considered the upgrade myself. I talked to the guys at Madrigal about the upgrade about a year ago. The reason it's a 331.5 and not 334 after the upgrade is because it will not be up to par with a 334. It will only bring you one step closer. I didn't think I could justify the cost at this point for myself.
Check out Larry Greenhill's review in the Sept. 99 Vol. 22 No. 9 Stereophile where he reviews the 334. He specifically talks about how the 331.5 relative to the 334 and 331. BTW, I am a very satified owner of a 331 as well. Good luck...
Thanks for the reply's. I will check out his review if I can get my hands on it. I was surprised to read some of the negative reviews (there were plenty of positives too) of the 331, 332 and 334 on Audioreview. It really baffles me because this amp is something special.