Hi rjh, I am actually going to post a TA piece tomorrow morning on EOS/ETH and ETH/USD which I think will illustrate an answer here.
For clarification - I see you said "... don't want to register it but plan to buy EOS again this summer" but you also said "OR just wait til June 1 to sell... perplexed". Are you trying to sell EOS prior to the June 1 date, but repurchase it after in hopes of a dip? Or are you basically just asking when you should sell and when/if you should repurchase?
Regardless of the answer above, I think EOS will be a smart HODL through at least February (I don't extend my TA estimate much further then that). Additionally, EOS is also releasing many goodies throughout all of 2018 so I think if you are going to HODL an Alt coin (aside from ETH), EOS is a good bet!